Question

Plz solve the following problem....

Answer 1

mine handwriting may trouble you

Answer 2

So lets tabulate 
People of age from 0 to 29 are 100
People of age from 30 to 39 are 220 - 100 = 120
People of age from 40 to 49 are 350 - 220 = 150
People of age from 50 to 59 are 750 - 350 = 400
People of age from 60 to 69 are 950 - 750 = 200
People of age from 70 to 79 are 1000 - 950 = 50
Mean = (sum of ages) / (total no. of people) = 
= ( for all ranges mean_range_age * no.of.people)/(total people)
total people = 1020
Mean = ( (29+0)/2 * 100 + (39+30)/2 * 120 + (49+40)/2 * 150
+  (59+50)/2 * 400 + (69+60)/2 * 200 + (79+70)/2 * 50 ) / 1020 = 51.3