Question

A natural no is chosen between 0 and 100. Find probability thst is is divisible by 7

Answer 1

14/99.

The total number of numbers divisible by 7 in [1, 99] are 14.

And the total numbers we are considering, are from 1 to 99, counting 99. (since the number is chosen between 0 and 100, 0 and 100 are excluded)

Now, I'm assuming I'm explaining to a 10-year-old.

You don't need to recite the table of 7 to count those that are divisible by it.

Simply begin dividing the (lowest - 1) and highest number in the range you are considering.

Here, we'll divide (1 - 1) and 99 by 7. We get 0 and 14 as the quotients.

14 - 0 is the number of numbers divisible by 7 in the given range.

Think about it, logically.

Now, the above trick is literally for kids. In a more advanced way of thinking, 0 is also divisible by 7 (since the remainder is 0), and the above doesn't account for that. You'll have to think about it when you face a question.

Answer 2

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Number of integers between 0 and 100 = n(S) = 99

• Let E be the event ‘integer divisible by 7’

Favourable outcomes to the event E = 7, 14, 21,…., 98

Number of favourable outcomes = n(E) = 14

Probability = P(E) = n(E)/n(S) = 14/99

Hope It's Helpful....:)