Project ForgeGeneral Aptitude
Quantitative Aptitude
GATE 2013
Medium
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?
- A13/90
- B12/90
- C78/90
- 77/90
Explanation
There are 90 two-digit integers (10 to 99). Multiples of 7 in that range: 14, 21, 28, ..., 98 — that's (98-14)/7 + 1 = 13 numbers. So 90 - 13 = 77 numbers are NOT divisible by 7, giving a probability of 77/90.
Source: GATE ME 2013 (Booklet Code A) (2013)
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