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Svetlana ran the first 5 kilometers of a 10-kilometer race a
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14 Jun 2018, 14:40
14 Jun 2018, 14:40
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Question Stats:
81% (02:04) correct
18% (02:26) wrong based on 82 sessions
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Svetlana ran the first 5 kilometers of a 10-kilometer race at a constant rate of 12 kilometers per hour. If she completed the entire 10-kilometer race in 55 minutes, at what constant rate did she run the last 5 kilometers of the race, in kilometers per hour?
(A) 15
(B) 12
(C) 11
(D) 10
(E) 8
(A) 15
(B) 12
(C) 11
(D) 10
(E) 8
Re: Svetlana ran the first 5 kilometers of a 10-kilometer race a
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07 Jul 2018, 04:32
07 Jul 2018, 04:32
Expert Reply
Explanation
To calculate Svetlana’s speed during the second half of the race, first calculate how long it took her to run the first half of the race. Svetlana ran the first 5 kilometers at a constant rate of 12 kilometers per hour.
These values can be used in the D = RT formula:
D(km)=R(km per hour) * T (hr)
Svetlana’s time for the first part of the race is \(\frac{5}{12}\)hours, or 25 minutes.
She completed the entire 10-kilometer race in 55 minutes, so she ran the last 5 kilometers in 55 – 25 = 30 minutes, or 0.5 hours. Now create another chart to find the rate at which she ran the last 5 kilometers:
5 = 0.5r
10 = r
Svetlana ran the second half of the race at a speed of 10 kilometers per hour.
To calculate Svetlana’s speed during the second half of the race, first calculate how long it took her to run the first half of the race. Svetlana ran the first 5 kilometers at a constant rate of 12 kilometers per hour.
These values can be used in the D = RT formula:
D(km)=R(km per hour) * T (hr)
Svetlana’s time for the first part of the race is \(\frac{5}{12}\)hours, or 25 minutes.
She completed the entire 10-kilometer race in 55 minutes, so she ran the last 5 kilometers in 55 – 25 = 30 minutes, or 0.5 hours. Now create another chart to find the rate at which she ran the last 5 kilometers:
5 = 0.5r
10 = r
Svetlana ran the second half of the race at a speed of 10 kilometers per hour.
Re: Svetlana ran the first 5 kilometers of a 10-kilometer race a
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19 Dec 2020, 05:40
19 Dec 2020, 05:40
Find time for the first 5 mile
as the speed is 12 m/h
so, 12 / 60 (mile/minutes) = 5 / M
=> M = 25 minutes
Now, we have 55-25 = 30 minutes
(30/60) X S = 5
=> (1/2) X S = 5
=> s = 10
as the speed is 12 m/h
so, 12 / 60 (mile/minutes) = 5 / M
=> M = 25 minutes
Now, we have 55-25 = 30 minutes
(30/60) X S = 5
=> (1/2) X S = 5
=> s = 10
