A bag contains green mints and red mints only. If $75 \%$ of the mints are green, what is the ratio of the number of green mints to the number of red mints?
(A) $3: 4$
(B) $3: 1$
(C) $4: 3$
(D) $1: 3$
(E) $3: 7$
Solution 1

Since the bag contains green mints and red mints only, the remaining $100 \%-75 \%=25 \%$ of the mints must be red.

Thus, the ratio of the number of green mints to the number of red mints is $75: 25=3: 1$.

Solution 2

Since $75 \%$ of the mints are green, then $\frac{3}{4}$ of the mints are green.

Since the bag contains only green mints and red mints, then $1-\frac{3}{4}=\frac{1}{4}$ of the mints in the bag are red.

Thus, there are 3 times as many green mints as red mints.

The ratio of the number of green mints to the number of red mints is $3: 1$.

ANSWER: (B)