---
title: Given that the probability of obtaining a rare item from a single bo… — Loot boxes and the surprise trap · tree and pragmatics
description: Given that the probability of obtaining a rare item from a single box is one per cent, select the statement consistent with the established facts concerning one hundred successive boxes. Exam question 2 of lesson 413 «Loot boxes and the surprise trap» of the everyday course of Mova's primary school,
---

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# Exam question 2 · Loot boxes and the surprise trap

<!-- .ven lang=en -->
Given that the probability of obtaining a rare item from a single box is one per cent, select the statement consistent with the established facts concerning one hundred successive boxes.

<!-- .vintro -->
**Mova's choice:** option 2 · **The right answer:** option 3 · wrong ✗ · **Who acts:** you, probability, established facts · **What happens:** give, obtain, be, select, establish, concern · **To what, where:** rare item, single box, one per cent, statement, hundred successive boxes

<!-- .vabout -->
This is exam question 2 of lesson 413 «Loot boxes and the surprise trap» of the everyday course of Mova's primary school, asked in stiff, formal language. The page gives the question's syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause, then the 4 options as the student saw them, each with its tree and pragmatics. Every text is parsed by Mova itself. How the student answered it, with the score of every option and why: [the test at school](https://md.mova.elamur.ai/free/en/school-run/everyday/413-loot-boxes-and-the-surprise-trap/#e2).

## The question {#question}

```conllu
# sent_id = question:everyday:413-loot-boxes-and-the-surprise-trap:e2:1
# text = Given that the probability of obtaining a rare item from a single box is one per cent, select the statement consistent with the established facts concerning one hundred successive boxes.
1	Given	give	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	19	advcl	_	_
2	that	that	SCONJ	IN	_	17	mark	_	_
3	the	the	DET	DT	Definite=Def|PronType=Art	4	det	_	_
4	probability	probability	NOUN	NN	Number=Sing	17	nsubj	_	_
5	of	of	SCONJ	IN	_	6	mark	_	_
6	obtaining	obtain	VERB	VBG	VerbForm=Ger	4	acl	_	_
7	a	a	DET	DT	Definite=Ind|PronType=Art	9	det	_	_
8	rare	rare	ADJ	JJ	Degree=Pos	9	amod	_	_
9	item	item	NOUN	NN	Number=Sing	6	obj	_	_
10	from	from	ADP	IN	_	13	case	_	_
11	a	a	DET	DT	Definite=Ind|PronType=Art	13	det	_	_
12	single	single	ADJ	JJ	Degree=Pos	13	amod	_	_
13	box	box	NOUN	NN	Number=Sing	9	nmod	_	_
14	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	17	cop	_	_
15	one	one	NUM	CD	NumForm=Word|NumType=Card	17	nummod	_	_
16	per	per	NOUN	NN	Number=Sing	17	compound	_	_
17	cent	cent	NOUN	NN	Number=Sing	1	advcl	_	SpaceAfter=No
18	,	,	PUNCT	,	_	1	punct	_	_
19	select	select	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
20	the	the	DET	DT	Definite=Def|PronType=Art	21	det	_	_
21	statement	statement	NOUN	NN	Number=Sing	19	obj	_	_
22	consistent	consistent	ADJ	JJ	Degree=Pos	19	xcomp	_	_
23	with	with	ADP	IN	_	26	case	_	_
24	the	the	DET	DT	Definite=Def|PronType=Art	26	det	_	_
25	established	establish	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	26	amod	_	_
26	facts	fact	NOUN	NNS	Number=Plur	22	obl	_	_
27	concerning	concern	VERB	VBG	VerbForm=Ger	26	acl	_	_
28	one	one	NUM	CD	NumForm=Word|NumType=Card	29	compound	_	_
29	hundred	hundred	NUM	CD	NumForm=Word|NumType=Card	31	nummod	_	_
30	successive	successive	ADJ	JJ	Degree=Pos	31	amod	_	_
31	boxes	box	NOUN	NNS	Number=Plur	27	obj	_	SpaceAfter=No
32	.	.	PUNCT	.	_	19	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **give** | participle | you *not said here* |  |  |  |  |  | vn break\_down-45.8 «NP V»: agent=Patient |
| 2 | **obtain** | gerund | the probability *not said here* | a rare item |  | a single box |  |  | vn obtain-13.5.2-1 «NP V NP PP.source»: agent=Agent item=Theme from box=Source |
| 3 | **is a** | present | the probability | one per cent |  |  |  |  | tree rules |
| 4 | **select** | imperative | you *not said here* | the statement |  |  |  | consistent *property* | vn obtain-13.5.2 «NP V NP»: agent=Agent statement=Theme |
| 5 | **establish** | participle |  |  |  |  |  |  | vn indicate-78-1-1 «NP V NP to be NP»: agent=Pivot |
| 6 | **concern** | gerund | the established facts *not said here* | hundred successive boxes |  |  |  |  | vn amuse-31.1 «NP V NP»: agent=Stimulus box=Experiencer |

<!-- .note -->
One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

## The options {#options}

### Option 1 {#o1}

<!-- .ven lang=en -->
The probability increases with each unsuccessful purchase until a rare item appears

```conllu
# sent_id = question:everyday:413-loot-boxes-and-the-surprise-trap:e2:o1:1
# text = The probability increases with each unsuccessful purchase until a rare item appears
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	probability	probability	NOUN	NN	Number=Sing	3	nsubj	_	_
3	increases	increase	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	with	with	ADP	IN	_	7	case	_	_
5	each	each	DET	DT	PronType=Tot	7	det	_	_
6	unsuccessful	unsuccessful	ADJ	JJ	Degree=Pos	7	amod	_	_
7	purchase	purchase	NOUN	NN	Number=Sing	3	obl	_	_
8	until	until	SCONJ	IN	_	12	mark	_	_
9	a	a	DET	DT	Definite=Ind|PronType=Art	11	det	_	_
10	rare	rare	ADJ	JJ	Degree=Pos	11	amod	_	_
11	item	item	NOUN	NN	Number=Sing	12	nsubj	_	_
12	appears	appear	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	advcl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **increase** | present | the probability |  |  |  |  | with each unsuccessful purchase | vn caused\_calibratable\_cos-45.6.2-1 «NP V ADV-Middle»: agent=Patient |
| 2 | **appear** | present | a rare item |  |  |  |  |  | vn appear-48.1.1 «NP V»: agent=Theme |

### Option 2 · ← Mova's choice {#o2}

<!-- .ven lang=en -->
A rare item is guaranteed within the first ten boxes

```conllu
# sent_id = question:everyday:413-loot-boxes-and-the-surprise-trap:e2:o2:1
# text = A rare item is guaranteed within the first ten boxes
1	A	a	DET	DT	Definite=Ind|PronType=Art	3	det	_	_
2	rare	rare	ADJ	JJ	Degree=Pos	3	amod	_	_
3	item	item	NOUN	NN	Number=Sing	5	nsubj:pass	_	_
4	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	5	aux:pass	_	_
5	guaranteed	guarantee	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
6	within	within	ADP	IN	_	10	case	_	_
7	the	the	DET	DT	Definite=Def|PronType=Art	10	det	_	_
8	first	first	ADJ	JJ	Degree=Pos|NumForm=Word|NumType=Ord	10	amod	_	_
9	ten	ten	NUM	CD	NumForm=Word|NumType=Card	10	nummod	_	_
10	boxes	box	NOUN	NNS	Number=Plur	5	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **guarantee** | present · passive |  | a rare item |  |  |  | within the first ten boxes | vn ensure-99 «NP V NP»: subject=Theme |

### Option 3 · ✓ the right answer {#o3}

<!-- .ven lang=en -->
A rare item is not guaranteed, and roughly one purchaser in three obtains none

<!-- fold The tree, 14 words -->
```conllu
# sent_id = question:everyday:413-loot-boxes-and-the-surprise-trap:e2:o3:1
# text = A rare item is not guaranteed, and roughly one purchaser in three obtains none
1	A	a	DET	DT	Definite=Ind|PronType=Art	3	det	_	_
2	rare	rare	ADJ	JJ	Degree=Pos	3	amod	_	_
3	item	item	NOUN	NN	Number=Sing	6	nsubj:pass	_	_
4	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	6	aux:pass	_	_
5	not	not	PART	RB	Polarity=Neg	6	advmod	_	_
6	guaranteed	guarantee	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	SpaceAfter=No
7	,	,	PUNCT	,	_	14	punct	_	_
8	and	and	CCONJ	CC	_	14	cc	_	_
9	roughly	roughly	ADV	RB	_	10	advmod	_	_
10	one	one	NUM	CD	NumForm=Word|NumType=Card	11	nummod	_	_
11	purchaser	purchaser	NOUN	NN	Number=Sing	14	nsubj	_	_
12	in	in	ADP	IN	_	13	case	_	_
13	three	three	NUM	CD	NumForm=Word|NumType=Card	11	nmod	_	_
14	obtains	obtain	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	6	conj	_	_
15	none	none	PRON	NN	PronType=Neg	14	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **not** **guarantee** | present · passive |  | a rare item |  |  |  |  | vn ensure-99 «NP V NP»: subject=Theme |
| 2 | **obtain** | present | one purchaser in three | none |  |  |  |  | vn obtain-13.5.2-1 «NP.asset V NP»: agent=Asset none=Theme |

### Option 4 {#o4}

<!-- .ven lang=en -->
A rare item is guaranteed upon the hundredth box, though not before it

```conllu
# sent_id = question:everyday:413-loot-boxes-and-the-surprise-trap:e2:o4:1
# text = A rare item is guaranteed upon the hundredth box, though not before it
1	A	a	DET	DT	Definite=Ind|PronType=Art	3	det	_	_
2	rare	rare	ADJ	JJ	Degree=Pos	3	amod	_	_
3	item	item	NOUN	NN	Number=Sing	5	nsubj:pass	_	_
4	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	5	aux:pass	_	_
5	guaranteed	guarantee	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
6	upon	upon	ADP	IN	_	9	case	_	_
7	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
8	hundredth	hundredth	ADJ	JJ	Degree=Pos	9	amod	_	_
9	box	box	NOUN	NN	Number=Sing	5	obl	_	SpaceAfter=No
10	,	,	PUNCT	,	_	13	punct	_	_
11	though	though	SCONJ	IN	_	13	mark	_	_
12	not	not	PART	RB	Polarity=Neg	13	advmod	_	_
13	before	before	SCONJ	IN	_	5	advmod	_	_
14	it	it	PRON	PRP	Case=Acc|Gender=Neut|Number=Sing|Person=3|PronType=Prs	13	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **guarantee** | present · passive |  | a rare item |  |  |  | upon the hundredth box | vn ensure-99 «NP V NP»: subject=Theme |

<!-- div src -->

**Text:** the tests of Mova's primary school, written for Mova (`world/data/school/`), as the course runner gave them to the student. **Trees:** Mova's own parse — the `en` model on the CPU, when the site is built — not checked by a teacher; they may be wrong. **Frames:** Mova's frames reader (`prag`), each text read on its own. Elamur Cosmic License.

<!-- /div -->

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