The mean age of Mr Jasmi, Miss Haslinda and their three children is 38 years. The mean age of their three children is 18 years. Calculate the mean age of Mr Jasmi and Miss has Linda

68

Explanation:

Let x be the age of Mr Jasmi
y be the age of Miss Haslinda
a + b + c be the age of the 3 children

We can write:
(x + y + a + b + c)/5 = 38

But:
(a + b + c)/3 = 18
a + b + c = 18(3)
a + b + c = 54

Substitute this value to our first equation

(x + y + 54)/5 = 38
x + y + 54 = 38(5)
x + y + 54 = 190
x + y = 190 - 54
x + y = 136

Thus:
Mean age of (mr jasmi and miss Linda) = (x+y)/2

But x + y = 136

=> mean age = 136/2 = 68