Answer:
see explanation
Step-by-step explanation:
(1)
Using the relationship
distance (d) = speed (s) × time (t)
The freight train leaves the station 1 hour earlier than the passenger train, so
d = 40(t + 1) ← Freight train
d = 50t ← Passenger train
We require to find when they are at the same distance from the station, then equating the 2 equations
50t = 40(t + 1) ← distribute
50t = 40t + 40 ( subtract 40t from both sides )
10t = 40 ( divide both sides by 10 )
t = 4
The passenger train will overtake the freight train after 4 hours
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(2)
let l represent length, then width = l - 32
perimeter (P) = 2l + 2w = 290, that is
2l + 2(l - 32) = 290 ← distribute and simplify left side
2l + 2l - 64 = 290
4l - 64 = 290 ( add 64 to both sides )
4l = 354 ( divide both sides by 4 )
l = 88.5 and w = 88.5 - 32 = 56.5
Then dimensions are 88.5 yards by 56.5 yards
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(3)
Plan A : 100 + 15n
Plan B : 25n
When is Plan A better than Plan B , that is
100 + 15n > 25n ( subtract 25n from both sides )
100 - 10n > 0 ( subtract 100 from both sides )
- 10n > - 100
Divide both sides by - 10, reversing the symbol as a result of dividing by a negative quantity.
n < 10
Plan A is better when number of hours (n) is less than 10
