Question

A pile of newspapers in Ms McGrath's art class was 17 3/4 inches high .Each Consecutive week,for the next 5 weeks,the height of the pile of newspapers increased by 8 7/12inches,What was the height ,in inches,of the pile after 3 weeks?

Answer 1

The height will be 79 inches after 3 weeks.

Explanation:

We are given that A pile of newspapers in Ms McGrath's art class was
`17 (3)/(4) = (71)/(4)`inches high

We are also given that each Consecutive week,for the next 5 weeks,the height of the pile of newspapers increased by
`8 (7)/(12) =(103)/(12)`inches

Now we are supposed to find What was the height ,in inches,of the pile after 3 weeks?

This situation is an AP

a =
`(71)/(4)`inches high

d =common difference =
`(103)/(12)`inches

Formula of sum of first n terms =
`S_n=(n)/(2)(2a+(n-1)d)`

`S_(3)=(3)/(2)(2((71)/(4))+(3-1)((103)/(12)))`

`S_(3)=(3)/(2)(2((71)/(4))+(3-1)((103)/(12)))`

`a_(3)=79`

Hence the height will be 79 inches after 3 weeks.