Question

A
jar contains 10 red marbles and 30 green Ones. How many red marbles
must   be added to the jar so that 60 % of the marbles will be red?

Answer 1

Answer:

Total Number of marbles present initially = 30 + 10 = 40 marbles

Let 'x' number of red marbles be added to the jar.

→ Total number of marbles = 40 + x

→ Number of Red marbles = 10 + x

We know that percentage of red marbles present be 60%. Therefore the remaining 40% is green marbles.

According to the question, we only add red marbles. So the number of green marbles remains the same. Therefore we get that,

→ 40% of ( 40 + x ) = 30

→ 40 ( 40 + x ) / 100 = 30

→ 1600 + 40 x = 30 × 100

→ 40 x = 3000 - 1600

→ 40 x = 1400

→ x = 1400 / 4

→ x = 35

Therefore 35 red marbles must be added to make the jar have 60% of red marbles.