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chetan2u
Could you understand what this question stem is?
I was left completely dumbfounded by the language used and also by the official solution provided by Bunuel above.
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Bunuel
An artist creates mosaics using stone tiles provided by his clients. A mathematician challenges him to make a series of large mosaics and a series of small mosaics following a few mathematical restrictions. Each large mosaic must have 85 tiles and each small mosaic must have 75 tiles. The total number of tiles in each series must be identical. What is the total number of mosaics the artist will create?

(1) The total number of mosaics in the series is less than 50.

(2) The number of small mosaics in the series is a prime number.


Mosaic is a design/pattern made by arranging tiles etc

Here, artist is asked to make certain large mosaics that consist of 85 tiles each and certain small mosaics that consist of 75 tiles each.
Now, set of large mosaics created and set of the small mosaics created contain similar number of tiles.

Thus, if the artist created x number of large mosaics, the number of tiles used is 85x and
y number of small mosaics will require 75y.
But the number of tiles used in each set is the same, so 85x=75y or 17x=15y.

What can we tell about x and y from 17x=15y.
As 17 and 15 are co prime, x will be a multiple of 15 and y will be a multiple of 17.
x can be 15, 30, 45….and so on
y can be 17, 34, 51….and so on.
Sets of (x,y) are (15,17), (30,34), (45,51) and so on

We have to find x+y?


(1) The total number of mosaics in the series is less than 50.
x+y<50.
Only possibility is the least value of the two => 15+17=32
The next higher value is 30+34=64>50
Sufficient

(2) The number of small mosaics in the series is a prime number.
y is a multiple of 17, so only possibility of y as a prime number is when it is 17 itself.
Thereafter, the values will be 17*2, 17*3 and so on.
Thus x+y = 15+17 = 32.
Sufficient


D


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Bunuel
An artist creates mosaics using stone tiles provided by his clients. A mathematician challenges him to make a series of large mosaics and a series of small mosaics following a few mathematical restrictions. Each large mosaic must have 85 tiles and each small mosaic must have 75 tiles. The total number of tiles in each series must be identical. What is the total number of mosaics the artist will create?

(1) The total number of mosaics in the series is less than 50.

(2) The number of small mosaics in the series is a prime number.


This question is a part of Are You Up For the Challenge: 700 Level Questions collection.
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Bunuel
An artist creates mosaics using stone tiles provided by his clients. A mathematician challenges him to make a series of large mosaics and a series of small mosaics following a few mathematical restrictions. Each large mosaic must have 85 tiles and each small mosaic must have 75 tiles. The total number of tiles in each series must be identical. What is the total number of mosaics the artist will create?

(1) The total number of mosaics in the series is less than 50.

(2) The number of small mosaics in the series is a prime number.
Bunuel, chetan2u - How can we confidently interpret Statement 1 to be talking about total number of mosaics in both the series? Isn't the wording ambiguous, like I assumed it's talking about total number of mosaics in any individual series (large or small) should be less than 50.
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