rheam25
A bag contains only two types of coins: 10 cent coins or 1 dollar coins and number of 10 cent coins does not exceed the number of 1 dollar coins. How many 10 cent coins are there in the bag?
(1) The total amount of money in the bag is $16.50.
(2) If five 10-cent coins are removed and replaced with five 1-dollar coins then two-third of all the coins in the bag are 1 dollar coins.
Let the number of 10 cent coins be \(t\) and the number of 1 dollar coins be \(d\) => \(t ≤ d\)
We need to determine the value of \(t\)
From statement 1: Total amount = 1650 cents \(=> 10t + 100d = 1650\)
\(=> t + 10d = 165\)
There can be two possible solutions for this: \(t = 5, d = 16\) OR \(t = 15, d = 15\) - Insufficient
From statement 2: If five 10-cent coins are removed and replaced with five 1-dollar coins then two-third of all the coins in the bag are 1 dollar coins
Number of 10 cent coins after 5 are removed = \((t - 5)\)
Number of 1 dollar coins after 5 are added = \((d + 5)\)
=> Total coins (remain unchanged) = \(t + d\)
\(=> \frac{(d+5)}{(t+d)} = \frac{2}{3}\)
\(=> 3d + 15 = 2t + 2d\)
\(=> d = 2t - 15\)
Multiple solutions exist: \(t = 20, d = 25\); \(t = 15, d = 15\); etc - Insufficient
Combining:
\(t + 10d = 165\)
\(2t - d = 15\)
Solving: \(d = t = 15\) -
SufficientAnswer C