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If a horse runs his first lap in 75 seconds, how long will it take the

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If a horse runs his first lap in 75 seconds, how long will it take the [#permalink]

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New post 19 Mar 2017, 06:00
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If a horse runs his first lap in 75 seconds, how long will it take the horse to complete three laps?

(1) Each lap the horse's speed decreased 20 percent from the previous lap.
(2) The horse will be racing against another horse whose speed increases 8% each lap and who completes three laps in 225 seconds.
[Reveal] Spoiler: OA

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Re: If a horse runs his first lap in 75 seconds, how long will it take the [#permalink]

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New post 19 Mar 2017, 17:05
If a horse runs his first lap in 75 seconds, how long will it take the horse to complete three laps?

To be able to answer this question, we need to know if the speed of the horse remains the same or increases/decreases in the remaining two laps.

Statement (1) Each lap the horse's speed decreased 20 percent from the previous lap.

This statement tells us that the speed of the horse decreases by 20% in each lap. We can use this to calculate the speed and hence the time taken to complete the remaining two laps. Hence this statement is sufficient.

Statement (2) The horse will be racing against another horse whose speed increases 8% each lap and who completes three laps in 225 seconds.

This statement gives information on another horse and hence is insufficient.

Answer is A
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Re: If a horse runs his first lap in 75 seconds, how long will it take the [#permalink]

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New post 19 Mar 2017, 19:07
(1) If the horse's speed decreased 20 percent from the previous lap then 75 - first lap, 60 - second lap 48 - third lap. And we are able to calculate how long it will take the horse to complete three laps. Sufficient
(2) We do not need to know the other horse speed to calculate how long it will take the horse to complete three laps. Insufficient

Answer: A
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Re: If a horse runs his first lap in 75 seconds, how long will it take the [#permalink]

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New post 19 Mar 2017, 23:22
matthewsmith_89 wrote:
(1) If the horse's speed decreased 20 percent from the previous lap then 75 - first lap, 60 - second lap 48 - third lap. And we are able to calculate how long it will take the horse to complete three laps. Sufficient
(2) We do not need to know the other horse speed to calculate how long it will take the horse to complete three laps. Insufficient

Answer: A



matthewsmith_89 Speed is inversely proportional to time, hence time should be increasing, not decreasing.
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Re: If a horse runs his first lap in 75 seconds, how long will it take the [#permalink]

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New post 20 Mar 2017, 04:31
Bunuel wrote:
If a horse runs his first lap in 75 seconds, how long will it take the horse to complete three laps?

(1) Each lap the horse's speed decreased 20 percent from the previous lap.
(2) The horse will be racing against another horse whose speed increases 8% each lap and who completes three laps in 225 seconds.


we need to know the speed or the time taken by horse in each lap
St 1: the speed relation for each lap is given. SUFFICIENT
ST 2: data for another horse is given without any link. INSUFFICIENT

Option A
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If a horse runs his first lap in 75 seconds, how long will it take the [#permalink]

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New post 20 Mar 2017, 18:37
If a horse runs his first lap in 75 seconds, how long will it take the horse to complete three laps?

(1) Each lap the horse's speed decreased 20 percent from the previous lap.
(2) The horse will be racing against another horse whose speed increases 8% each lap and who completes three laps in 225 seconds.


Answer should be A since it tells about the horse's speed and provide enough data points to calculate its speed (decrease 20% every lap in this case). Hence sufficient

However, statement (2) tells us speed of another horse which is really not helpful in knowing the speed of Original Horse. Hence Insufficient
If a horse runs his first lap in 75 seconds, how long will it take the   [#permalink] 20 Mar 2017, 18:37
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