Question

ANSWER ASAP The ratio of red marbles to blue marbles in a jar is 3 to 8. There are 40 blue marbles in the jar. How many red marbles are in the jar? A. 5 B. 15 C. 24 D. 35

Answer 1

If the ratio of red marbles to blue marbles in a jar is 3 to 8, the meaning is for every 3 red marbles there are 8 blue marbles.
3 red marbles------------------8 blue marbles.

ratio=3/8

we have 40 blue marbles; we have to compute the number of red marbles.

1) Method 1; by the rule three.

3 red marbles-----------------8  blue marbles
x----------------------------------40 blue marbles

x=(3 red marbles * 40 blue marbles) / 8 blue marbles=15 red marbles.

answer: B. 15

Method 2: the ratio of red marbles to blue marbles is
ratio=number of red marbles / number of blue marbles
ratio=3/8

if we want to compute the number of red marbles we have to multiply the number of blue marbles by this  ratio.

number of red marbles=ratio (red/blue)* number of blue marbles
number of red marbles=(3/8)*40=15

Answer: B.15