SOLUTION: Carl and Kyle leave Kyle's house at the same time. Carl drives north and Kyle drives West. Carl's average speed is 9 mph slower than Kyle's. At the end of one hour, they are 45 mil

Question 275955: Carl and Kyle leave Kyle's house at the same time. Carl drives north and Kyle drives West. Carl's average speed is 9 mph slower than Kyle's. At the end of one hour, they are 45 miles apart. Find the average speed of Kyle. (Round off your answer to the nearest tenth).
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Carl and Kyle leave Kyle's house at the same time.
Carl drives north and Kyle drives West.
Carl's average speed is 9 mph slower than Kyle's.
At the end of one hour, they are 45 miles apart.
Find the average speed of Kyle. (Round off your answer to the nearest tenth).
:
Let s = K's driving speed
then
(s-9) = C's driving speed
:
Solve this as a right triangle: a^2 + b^2 = c^2
where the distance after 1 hr is:
a = 1s
b = 1(s-9)
c = 45
:
s^2 + (s-9)^2 = 45^2
A quadratic equation
s^2 + s^2 - 18s + 81 = 2025
:
2s^2 - 18s + 81 - 2025 = 0
:
2s^2 - 18s - 1944 = 0
Simplify, divide by 2
s^2 - 9s - 972 = 0
Fortunately this will factor
(s - 36)(s + 27) = 0
Positive solution
s = 36 mph is K's speed
:
:
Check solution using a calc:
Enter: = 45; confirms our solution
RELATED QUESTIONS
Neville and Carl both leave Perth at the same time to go on holidays. Neville travels by... (answered by ikleyn)

Emma drives 6 miles east and 5 miles north to get home from work. Kyle drives 2 miles... (answered by Alan3354)

Carl and Antonio are friends who live 20 miles apart. They are making plans to meet up.... (answered by stanbon)

Kyle and Tony are driving in two different cars towards the same destination 587 miles... (answered by richwmiller)

Carl and Dennie's are brothers. The sum of their ages is 29. In 6 year's time Carl will... (answered by josgarithmetic,greenestamps)

Kyle and Tony are driving to the same destination 587 miles away, starting at the same... (answered by stanbon)

Kyle and Zoey have 135 crayons altogether. The number of crayons Kyle has is equal to 50% (answered by ikleyn,Alan3354)

Matt and Chris leave their uncle's house in Phoenix at the same time. Matt drives west on (answered by josgarithmetic)

George and Carl are college roommates and are heading to their own homes for spring... (answered by richwmiller)