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A railroad crew can lay 7 miles of track each day. They need to lay 196 miles of track. The length, L (in miles), that is left to lay after d days is given by the following function.

=Ld−1967d

(a)

How many miles of track does the crew have left to lay after

17

days?

(b)

How many days will it take the crew to lay all the track?

days

Jan 18, 2018

#1
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(a)

well since they can lay 7 miles of track every day, the formula i make for the amount of track there is left to lay is:

$$l=196-Ld$$

where l is the length of track remaining, L is the length of track they can lay in one day and d is the number of days.

so we replace L for 7 and d for 17 and we get:

$$l=196-7\times17$$

whichworks out to be 77 miles of track remaining to lay.

(b)

well since we want them to have 0 length of track remaining, and they can lay 7 miles of track a day, we can work out d. let's give the formula a bash to get:

$$d=\frac{196-l}{L}$$

we then replace l with 0 and L with 7 and get:

$$d=\frac{196}{7}$$

which works out to be 28. so it will take 28 days or 4 weeks for the railroad crew to lay 196 miles of track.

Jan 18, 2018