Question

Let S be the sample space of all five digit numbers. It p is the probability that a randomly selected number from S , is multiple of 7 but not divisible by 5, then 9 p is equal to

• A. 1.0146
• B. 1.2085
• C. 1.0285
• D. 1.1521

Answer 1

Answer: (C)

1.0285

Answer 2

The correct answer is (C):
Among the 5 digit numbers,
First number divisible by 7 is 10003 and last is 99995.
⇒ Number of numbers divisible by 7.
= $\frac{99995-10003}{7} + 1$
= 12875
First number divisible by 35 is 10010 and last is 99995.
⇒ Number of numbers divisible by 35 =$\frac{ 99995-10010}{35}+1 = 2572$
Hence number of number divisible by 7 but not by 5
= 12857 – 2572
= 10285
9P =$\frac{10285}{90000} × 9$
= 1.0285