Asif1234 wrote:
A school supply store sells only one kind of desk and one kind of chair, at a uniform cost per desk or per chair. If the total cost of 3 desks and 1 chair is twice that of 1 desk and 3 chairs then the total cost of 4 desks and 1 chair is how many times that of 1 desk and 4 chairs?
(A) 5 (B) 3 (C) 8/3 (D) 5/2 (E) 7/3
Let the cost of a chair and a desk be $c and $d respectively.
We have: cost of 3 desks and 1 chair is twice that of 1 desk and 3 chairs
=> 3d + c = 2(d + 3c)
=> 3d + c = 2d + 6c
=> d = 5c ... (i)
We need to find: total cost of 4 desks and 1 chair is how many times that of 1 desk and 4 chairs
i.e. (4d + c)/(d + 4c) = (4*5c + c)/(5c + 4c) = 21c/9c = 7/3
Answer E