Latest CAT Aptitude Question SOLUTION: 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)

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(#M40021534) CAT Numerical Ability question Keep an EYE

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

Asked In CAT dipali (10 years ago)

Solved Rahul Kumar Mehta Read Solution (4)

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Read Solution (4) :

Rahul Kumar Mehta  (10 years ago)

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 .

Is this solution Helpfull? Yes (11) | No   

karthigabalamurugan  (10 years ago)

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

Is this solution Helpfull? Yes (3) | No   

Md.Sultan Khichi  (10 years ago)

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.

Is this solution Helpfull? Yes (2) | No   

Animesh  (10 years ago)

1-(13/90)=77/90

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