Out of all the 2-digit integers between 1 and 100, a 2-digit number has to be selected at random. What is the probability that the selected number is not divisible by 7?
option
(A) 13/90
(B) 12/90
(C) 78/90
(D) 77/90

• Option (D) will be the answer
  
  Reason - There are 90 two digit integers between 1 and 100 and these are
  
  10,11,12,........ till 99
  
  First find the probability that the selected number is divisible by 7 and after that we will subtract that probability from 1 in order to get the probability that the selected number is not divisible by 7
  
  we have 10,11,12,13,14,........,98,99
  
  The first number which is divisible by 7 is 14
  
  and the last number which is divisible by 7 is 98
  
  Now by using formula (98 - 14)/7 + 1 = 12 + 1 = 13
  
  so we have total 13 two digit integers which is divisible by 7 between 1 and 100
  
  Now in order to get the probability that the selected number is not divisible by 7 we have to subtract 13/90 from 1
  
  so [ 1 - (total two digit integers which is divisible by 7)/ total number ]
  
  1 - 13/90 = 77/90 is the answer .
• 11 years agoHelpfull: Yes(11) No(0)
• ANS: 77/90
  bocoz, 2 digit intergers between 1 and 100 is (10-99)ie)90 numbers not divisible b 7 is (14,21,28,35,42,59,56,63,70,77,84,91,98 )ie)13 integers are not divisible by 7.hence the probability that the selected number is not divisible by 7 is 77/90
• 11 years agoHelpfull: Yes(3) No(0)
• Total no. of 2 digit no. btwn 100 are 90.
  Total no. which are divisible by 7 are 13.
  Probability of no. divsible by 7 is 13/90.
  Probability of no. not divsible by 7 is 1-13/90=77/90.
  Ans:d.77/90.
• 11 years agoHelpfull: Yes(2) No(0)
• 1-(13/90)=77/90
• 11 years agoHelpfull: Yes(0) No(0)