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Keren rode her moped from home to the beach at an average speed of 20
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26 Sep 2025, 00:41
26 Sep 2025, 00:41
Expert Reply
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Question Stats:
85% (01:29) correct
14% (01:11) wrong based on 7 sessions
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Keren rode her moped from home to the beach at an average speed of 20 miles per hour. She rode back at an average speed of 30 miles per hour. What was her average speed for the entire trip, in miles per hour?
A. 20
B. 21
C. 22
D. 23
E. 24
A. 20
B. 21
C. 22
D. 23
E. 24
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Re: Keren rode her moped from home to the beach at an average speed of 20
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16 Oct 2025, 13:02
16 Oct 2025, 13:02
Expert Reply
To calculate Keren's average speed for the entire trip (to and from the beach), use the formula for average speed when distances are equal and speeds vary:
$$
\(\text { Average speed }=\frac{2 \times v_1 \times v_2}{v_1+v_2}\)
$$
where $\(v_1=20 \mathrm{mph}\)$ (to the beach), and $\(v_2=30 \mathrm{mph}\)$ (back home).
Calculate:
$$
\(\frac{2 \times 20 \times 30}{20+30}=\frac{1200}{50}=24\)
$$
So the average speed for the entire trip is 24 mph .
Answer:
E. 24
$$
\(\text { Average speed }=\frac{2 \times v_1 \times v_2}{v_1+v_2}\)
$$
where $\(v_1=20 \mathrm{mph}\)$ (to the beach), and $\(v_2=30 \mathrm{mph}\)$ (back home).
Calculate:
$$
\(\frac{2 \times 20 \times 30}{20+30}=\frac{1200}{50}=24\)
$$
So the average speed for the entire trip is 24 mph .
Answer:
E. 24
gmatclubot
Re: Keren rode her moped from home to the beach at an average speed of 20 [#permalink]
16 Oct 2025, 13:02
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