kunti had 5 children each one born in continuous year. Arjun have two elder and two younger brother. (For example age will be 1,2,3,4,5). Kunti remember the multiplication of there ages. She multiply the ages of son's after the youngest brother become 1 year old and skipping arjun's age. Multiplication always will be?
a) a prime number minus 1
b) divisible by 10
c)addition of two perfect square
d)subtraction of two perfect square

• option d)
  
  the ages of five brothers can be any consecutive integers lets say
  
  1,2,3,4,5 or 2,3,4,5,6 or 3,4,5,6,7 or 4,5,6,7,8
  
  the age of arjun is the middle one and on skipping that the multiplication of above examples will be
  
  40,180,504,1120
  
  all of these can be obtained from difference between two perfect squares
  
  40=49-9
  
  180=196-16
  
  504=625-121
  
  1120=1156-36
• 10 years agoHelpfull: Yes(26) No(5)
• (c)
  as question says that Kunti does the multiplication when youngest brother become one year old then age of all the brother will be 1,2,3,4,5.
  then Arjun's age=3 (will not use in multiplication)
  then no's left for multiplication are 1,2,4,5.
  only three numbers will be selected for multiplication.
  then combinations will be-
  1,2,4 >> 8 (4+4)
  1,2,5 >> 10 (1+9)
  1,4,5 >> 20 (4+16)
  2,4,5 >> 40 (4+36)
  so these multiplications will be addition of two perfect square.
  
  
  
• 10 years agoHelpfull: Yes(5) No(4)
• D. Subtraction of perfact square.
• 10 years agoHelpfull: Yes(4) No(0)
• a
  because 2*4*5=40
  and 41 is the prime number so option a is correct
• 10 years agoHelpfull: Yes(3) No(10)
• Ans d
  Ex 3*3-2*2=5
• 10 years agoHelpfull: Yes(3) No(0)
• a and b both are right
• 10 years agoHelpfull: Yes(2) No(4)
• She multiply the ages of son's after the youngest brother become 1 year old.so,the age of youngest boy should be 1year.so how we can take 2,3,4,5 etc
  
• 10 years agoHelpfull: Yes(2) No(1)
• hi@priyanka
  if yoy take different examples as i do then the age of the sons after multiplication will become 20*2,30*6,42*12,56*20
  so it is not always true that there product will be divisible by 10
• 10 years agoHelpfull: Yes(1) No(0)
• It must have one answer only.. it was in today's elitmus paper.
• 10 years agoHelpfull: Yes(0) No(0)
• Kumar it is just an example given in the question.you can take whatever consecutive values you would like to take a
• 10 years agoHelpfull: Yes(0) No(0)
• with what approach u have solved it-prateek
  Pandey
• 10 years agoHelpfull: Yes(0) No(0)
• hi @ Prateek pandey why option b is wrong.. i m nt getting. please explain.
• 10 years agoHelpfull: Yes(0) No(0)
• d,as the ages of 5 children be any consecutive no. like 1,2,3,4,5 or 2,3,4,5,6
  A/Q Arjun is on the middle $ his age's is skipped by his mother.so the multiplication be 40 or 180 both are the substraction of two perfect square.
• 10 years agoHelpfull: Yes(0) No(0)
• let x is the age of arjun so x-2 , x-1 , x, x +1,x+2 are age..
  now multiply this. x(x^2 - 1)(x^-4) always indivisible by 10 exmple
  x=3, 3*8*5= 120, and 4*15*12= 720.
• 10 years agoHelpfull: Yes(0) No(0)
• Haii @prateek tell me one thing, u considered only skipping arjun's age but u r not considering she multiply after youngest child become one year.
  if i m considered 2,3,4,5,6 =180 but i think so 2-1,3,4,5,6=90 because she multiply after youngest child become 1 yr old.
  if considerd 3,4,5,6,7 in which 3-1,4,5,6,7 .....m i right ?? if not then plz give valuable answer.
• 10 years agoHelpfull: Yes(0) No(1)
• opt d. Because for each set of nos. it will satisfy .
• 10 years agoHelpfull: Yes(0) No(0)