Question

On monday, mary had 23 bananas. On tuesday, her family ate half of them. On wednesday they ate half of the remaining bananas. If they continue each day, on which day of the week will there only be one banana left

Answer 1

Friday.

Explanation:

The number of bananas is reducing from 23 at a rate of 50% of the previous day's number.

Given that on Monday, Mary had 23 bananas and we are asked that on which day there will be only 1 banana will left.

Let after d days the remaining bananas will become one.

Therefore,
`23[1-(50)/(100) ]^(d) = 1`

⇒
`(0.5)^(d) =(1)/(23)`

Taking log both sides we get

`d \log 0.5 = \log ((1)/(23) )`

⇒ d = 4.523 days.

Therefore, on Friday the remaining number of bananas will become 1. (Answer)