Let speed of the boat in still water = x miles per hour
Let speed of the current = y miles per hour
When water and current both flow in same direction then effective speed will be sum of both speeds that is (x+y)
now plug the given values in formula speed=distance/time
we get equation:
(x+y)=160/8
or x+y=20...(i)
When water and current both flow in opposite direction then effective speed will be difference of both speeds that is (x-y)
now plug the given values in formula speed=distance/time
we get equation:
(x-y)=160/40
or x-y=4
or x=4+y...(ii)
plug value of x into (i)
4+y+y=20
4+2y=20
2y=16
y=8
plug value of y into (ii)
x=4+8=12
Hence final answer is given by:
Speed of the boat in still water = 12 miles per hour
Speed of the current = 8 miles per hour
the amount of time of the two trips is a proportional relationship
<h3>What is proportional relationship?</h3>
mathematical expressions are said to be proportional if there unit rate are equal. this means that the expressions will give similar results when similar values are substituted into the equation.
<u>solution:</u>
Driving 7 hrs within 385 miles represents a unit rate of 385 / 7 = 55 miles per hour or 55 mph
while 3 hrs in 165 miles represents a unit rate of 165 / 3 = 55 mph
since both situations gave similar speed in miles per hour they are said to have a proportional relationship.
Read more on proportional relationship here: brainly.com/question/12242745
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Answer:
4
Step-by-step explanation:
1.b
2.c
3.d
4.g
