Question

A watermelon consists of 90% water and 10% pulp. After drying the weight is 20 kg

Answer 1

Answer: 40kg

Explanation: If 40% water and 10% pulp (Total 50%) is 20kg
Then 90% water and 10% pulp (Total 100%) would be double, so therefore 40kg

To confirm: 10% = 4kg
40kg - 4kg = 36kg
to get from 90% to 40% just divide by 2.25
the answer is 16kg
add on the pulp weight of 4kg = 20kg

Answer 2

Answer: 40kg

Explanation:

Let x be the initial weight:

90% + 10% = x
100% = x

40% + 10% = 20kg
50% = 20kg

=> 100/50= x/20
=> 2 = x/20
=> x = 20 x 2
=> x = 40kg

Therefore the initial weight is 40kg