Question

The average of 4 silbings is 12.5 years if 3 of the silbings are 12 years old triplets how old is the fouth silbing????

Answer 1

let the age of each of the siblings be a,b,c,d respectively.
then the average age is
(a+b+c+d)/4 = 12.5
now 3 are 12, so plug these values in,
(12+12+12+d)/4=12.5
36+d=50
d=14

Answer 2

\[\frac{12+12+12+x}{4}=12.5\]

Answer 3

bee is right thx