Question

Aubrey has a shelf full of books.
• Exactly 1} 3
of the books on the shelf are mysteries.
• Aubrey has read 10 of the mysteries on the shelf.
• The number of mysteries Aubrey has read is greater than }1 5
of the number of
mysteries on the shelf and less than }1 4
of the number of mysteries on the shelf.
Which could be the number of books on the shelf?
A. 120 B 140 c 147 D 150
please help which one is answer

Answer 1

Study MathMate's answer to your question.

http://www.jiskha.com/display.cgi?id=1428456770

Answer 2

x=number of mystery books. 3x=total number of books on the shelf.

x/5<10<x/4 is given. Get rid of the fifths and quarters by multiplying by 20.

4x<200<5x --> 40<x<50.
The number of mystery books is anything between 40 and 50, multiply by 3 and you have your total.

Answer 3

1/3x1/5=1/15
1/3x1/4=1/12
She read 10 books, so it can't be just a range from 12-15 books, so it's 120-150 books. Since it's greater or less, it can't be 120 or 150.
It also says exactly 1/3, so the answer is 147 books. The number divisible by 3.

Answer 4

120