How many different integers can be expressed as the sum of three distinct numbers from the set {3, 10, 17, 24, 31, 38, 45, 52}?
option
a) 8
b) 56
c) 16
d) 15

• its is 8C3= (8x7x6)/(3x2x1) =56
• 10 years agoHelpfull: Yes(50) No(33)
• Interesting question. If you think that 8C3 = 56 is correct then it is wrong answer. We are not asked how many ways we can select 3 numbers out of 8. But how many different numbers can be expressed as a sum of three numbers from the given set. For example, 3 + 10 + 31 = 3 + 17 + 24 = 47. So 47 can be expressed as a sum of 3 numbers in two different ways but 47 should be considered as only one number.
  Now the minimum number that can be expressed as a sum of 3 numbers = 30. The next number is 37. Similarly the largest number is 38 + 45 + 52 = 135.
  So there exists many numbers in between, with common difference of 7.
  Total numbers = l−ad+1=135−307+1 = 16.
  
• 8 years agoHelpfull: Yes(20) No(2)
• 3+10+17=30,3+10+24=37,3+10+31=44.............38+45+52=135 i.e highest number. So,numbers are 30,37,44,51,...........135. It is in A.p
  a+(n-1)d=135,here a=30,d=7
  30+(n-1)7=135
  n=16
• 7 years agoHelpfull: Yes(19) No(0)
• 16 is answer
• 10 years agoHelpfull: Yes(13) No(22)
• 8c3 is the write ans
• 10 years agoHelpfull: Yes(6) No(10)
• 56 is the correct one
• 10 years agoHelpfull: Yes(6) No(7)
• 8C3 = 8!/3!*5!=8*7*6/3*2=56
• 10 years agoHelpfull: Yes(4) No(9)
• answer is 15
  because min value of 3 sum is = 3+10+17=30
  max value of 3 sum is =38+45+52=135
  
  = (135-30/7)+1=15
• 7 years agoHelpfull: Yes(4) No(2)
• sory frnds answer is 16 because
  
  (135-30/7)+1=15+1
  
• 7 years agoHelpfull: Yes(3) No(0)
• For every combination only 2 distinct number can be obtained so 8 *2= 16
• 5 years agoHelpfull: Yes(0) No(0)
• (((maximum of 3 number)-(minimum of 3 number))/ difference between them) +1
  
  ex:-(((52+45+38) - (3+10+17)) / 7 ) + 1 = 16
• 5 years agoHelpfull: Yes(0) No(0)