Question

Four sister are 30 months apart in age. If the sum of their ages is 31 years how old is the yougest sister

Answer 1

Answer:

Step-by-step explanation:

The sisters are 30 months apart in age. 30 months is the same as 2.5 years (30 months = 12 + 12+ 6= 2 and half years = 2.5 years)

Let the age of the youngest sister be X

The age of second youngest = X + 2.5

The age of Second to elder = X + 2.5 + 2.5 = X + 5

The age of the eldest sister = X + 5 + 2.5 = X + 7.5

The sum of ages of 4 sisters is 31. Hence,

X + (X + 2.5 ) + (X + 5 ) + (X + 7.5) = 31

X + X + 2.5 + X + 5 + X + 7.5 = 31

3X + 15 = 31

On subtracting 15 from both sides :

3X = 31 - 15

3X = 16

On dividing both sides with a 3 :

X = 16/ 3

X = 5.33333 = 5 + (1/3) = 5 years and (1/3) years

= 5 years and (12* 1/3 ) months = 5 years and 4 months

The youngest sister is 5 years and 4 months old