Question

A small plant is 2 and 1/2 inches tall. How tall will it be in 3 weeks if it grows 3/4 inch each week. Which method will NOT give the correct number of inches

Answer 1

A method which will not give the correct answer is simply doing 2.5 times 0.75

Answer 2

Total length of the plant in week is
`(19)/(4) inches`

Explanation:

Length of the small plant =
`2(1)/(2) inches=(5)/(2) inches`

Rate at which plant in growing =
`r=(3)/(4) inch/week`

Length of the plant increased in 3 weeks = x

`x=r* 3weeks=(3)/(4) inch/week* 3weeks =(9)/(4) inches`

Total length of the plant =
`(5)/(2)inches+x`

`(5)/(2)inches+(9)/(4) inches`

=
`(20+18)/(2* 4) inches`

`=(38)/(8) inches=(19)/(4) inches`