Question

Since Scott started doing his work out plan Janet has been inspired to set her self a goal to do more exercise and walk a little more each day. She has decided to walk 10 meters more everyday. On the day 20 she walked 800 meters. How many meters will she walk on day 21?On day 60?

Answer 1

Day 21: 810 m

Day 60: 1,200 m

Explanation:

The amount of meters she walk everyday can be modeled as a linear function, as the rate of variation is a constant (10 m/day):

`dD/dt=10\;\text{m/day}`

This constant (10 m/day) is the slope of the linear function.

We know one point of the linear function (D(20)=800) and the slope, so we can calculate the y-intercept:

`D(t)=10t+b\\\\D(20)=10*20+b=800\\\\b=800-10*20=800-200\\\\b=600`

Now, we can calculate the distance she walks by day 21 and day 60:

`D(21)=10*21+600=210+600=810\\\\\\D(60)=10*60+600=600+600=1,200`