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# A box of chocolates has 15 rows with 10 spaces for chocolates in each

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Math Expert
Joined: 02 Sep 2009
Posts: 58395
A box of chocolates has 15 rows with 10 spaces for chocolates in each  [#permalink]

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07 Jan 2018, 23:06
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Difficulty:

45% (medium)

Question Stats:

69% (01:18) correct 31% (01:57) wrong based on 21 sessions

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A box of chocolates has 15 rows with 10 spaces for chocolates in each row, how many chocolates are in the box?

(1) There is an average (arithmetic mean) of 6 empty spaces in the first 8 rows.
(2) There is an average (arithmetic mean) of 9 empty spaces in the last 9 rows.

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Re: A box of chocolates has 15 rows with 10 spaces for chocolates in each  [#permalink]

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08 Jan 2018, 11:39
Bunuel wrote:
A box of chocolates has 15 rows with 10 spaces for chocolates in each row, how many chocolates are in the box?

(1) There is an average (arithmetic mean) of 6 empty spaces in the first 8 rows.
(2) There is an average (arithmetic mean) of 9 empty spaces in the last 9 rows.

So 15 rows, 10 spaces in each row. Any non-empty space is occupied by chocolate.

(1) In the first 8 rows, average empty spaces per row = 6, so total empty spaces = 6*8 = 48. So out of 80 total spaces, 48 are empty. Thus 80-48 = 32 have chocolates. But no data about other rows. Insufficient.

(2) In the last 9 rows, average empty spaces per row = 9, so total empty spaces = 9*9 = 81. So out of 90 total spaces, 81 are empty. Thus 90-81 = 9 have chocolates. But no data about other rows. Insufficient.

Combining the statements, we have first 8 rows and last 9 rows. 8+9 = 17, but there are total 15 rows only. So there is an overlap of 2 rows between first and second statements, of which we have no data per se. Until we know the number of chocolates in those 2 rows (7th, 8th from top Or 8th,9th from bottom) we cannot answer this question. Hence E answer
Re: A box of chocolates has 15 rows with 10 spaces for chocolates in each   [#permalink] 08 Jan 2018, 11:39
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