By , 8 months ago

Ques 5 :  Given three years ago average age of 5 members = 17 years
                 So 3 years ago the sum of their ages would be  = 17 x 5 = 85 years.
   
   At present the average age of family ( 5 members + baby ) = 17
    Sum of ages of 5 members + baby = 17 x 6 = 102

 Also during these  3 years , the ages of  all the 5 members has increased by three years
 So in total the ages have increased by 3 x 5 = 15 years
   Present sum of ages of 5 members = 85 + 15 = 100

 So age of baby = Sum of ages of ( 5 members + baby ) - Sum of ages of 5 members
                        = 102 - 100 = 2 years

Ques 10 :  There are 7 members in team 1 and their average age = 66 kg
                So sum of weights of this team = 7 x 66 = 462 kg
              Similarly there are 5 members in team 2 and their average age = 64 kg
                 Sum of weights of this team = 5 x 64 = 320 
           When they are combined , the total of weights of all the members = 462 + 320 = 782
           Total number of members = 7 + 5 = 12
          New average = 782/12 = 65.16
  This should be the actual answer.