Question

The average age of a b and c is 40 years.if the average age of b is (9/10) of this average,what is the average age of a and c together?

Answer 1

Answer:

42

Step-by-step explanation:

given that [a+b+C]/3 = 40

hence [a+b+C] = 40*3

[a+b+C] = 120

also give that b =9/10 of 40

b = 9*4

b = 36yrs

from above [a+b+C] = 120

[a+36+C] = 120

[a+C] = 120-36

[a+C] = 84

dividing both side by 2

[a+C]/2 = 84/2

[a+C]/2 = 42

hence average of a and c is 42 years

Answer 2

Answer:

42 years

Step-by-step explanation:

$according \: to \: question \: \\ average \: age \: of \: abc = 40years \\ sum \: of \: ages \: of \: abc = 40 \times 3 = 120 \: years \\ also \\ age \: of \: b = \frac{9}{10} \times 40 = 36\\ now \: we \: know \: that \\ age \: of \: a + b + c = 120 \: years \: \\ and \: age \: of \:b = 36 \: years \\ then \: a + c = 120 - 36 = 84 \: years \\ age \: of \: a + c = 84 \: years \: so \: average \: of = \\ \frac{84}{2} = 42years$