21. In a group of 5 families, every family has a certain number of children, such that the number of children forms an arthmetic progression with a common difference of one, starting with two children in the first family. Despite the objection of their parents every child in a family has three times as many pets to look after as the number of offspring in the family. What is the total number of pets in the entire group of five families.

• answer is 270.
  Number of children= 2,3,4,5,6
  no. of pets=2*2+ 3*3 + 4*4 + 5*5 +6*6 =90
  it is given that 3 times as many pets = 90*3 = 270.
• 5 years agoHelpfull: Yes(7) No(0)
• I think answer is 60
• 5 years agoHelpfull: Yes(1) No(1)
• As the number of children are in arithmetic progression starting with 2, the five families have 2, 3, 4, 5, 6 kids respectively.
  As each children has kept the pets equal to the number of kids in the family, Each family has n^2 pets.
  So total = 2^2+3^2+4^2 +5^2 +6^2 = 90
• 5 years agoHelpfull: Yes(1) No(0)
• Explanation:
  
  As the number of children are in arithmetic progression starting with 2, the five families have 2, 3, 4, 5, 6 kids respectively. As each children has kept the pets equal to the number of kids in the family, each family has n2 pets. So total = 22+32+42 +52 +62 = 90
• 3 Months agoHelpfull: Yes(0) No(0)