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During a trip that they took together, Carmen, Juan, Maria, a
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21 Jun 2018, 08:07

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3

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Question Stats:

97% (00:59) correct 3% (01:26) wrong based on 600 sessions

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During a trip that they took together, Carmen, Juan, Maria, and Rafael drove an average (arithmetic mean) of 80 miles each. Carmen drove 72 miles, Juan drove 78 miles, and Maria drove 83 miles. How many miles did Rafael drive?

During a trip that they took together, Carmen, Juan, Maria, a
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21 Jun 2018, 17:33

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Bunuel wrote:

During a trip that they took together, Carmen, Juan, Maria, and Rafael drove an average (arithmetic mean) of 80 miles each. Carmen drove 72 miles, Juan drove 78 miles, and Maria drove 83 miles. How many miles did Rafael drive?

Re: During a trip that they took together, Carmen, Juan, Maria, a
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21 Jun 2018, 18:00

Bunuel wrote:

During a trip that they took together, Carmen, Juan, Maria, and Rafael drove an average (arithmetic mean) of 80 miles each. Carmen drove 72 miles, Juan drove 78 miles, and Maria drove 83 miles. How many miles did Rafael drive?

During a trip that they took together, Carmen, Juan, Maria, a
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21 Jun 2018, 18:02

4

During a trip that they took together, Carmen, Juan, Maria, and Rafael drove an average (arithmetic mean) of 80 miles each. Carmen drove 72 miles, Juan drove 78 miles, and Maria drove 83 miles. How many miles did Rafael drive?

Re: During a trip that they took together, Carmen, Juan, Maria, a
[#permalink]

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23 Jul 2018, 17:41

1

Bunuel wrote:

During a trip that they took together, Carmen, Juan, Maria, and Rafael drove an average (arithmetic mean) of 80 miles each. Carmen drove 72 miles, Juan drove 78 miles, and Maria drove 83 miles. How many miles did Rafael drive?

A. 80

B. 82

C. 85

D. 87

E. 89

We can create the equation:

(72 + 78 + 83 + x)/4 = 80

233 + x = 320

x = 87

Alternate Solution:

Carmen drove 8 miles under the average, Juan drove 2 miles under the average and Maria drove 3 miles above the average. If we add these up, we get -8 + (-2) + 3 = -7; which means we are 7 miles under the average. Therefore, Rafael must drive 7 miles over the average to keep the average at 80 miles. Thus, Rafael drove 80 + 7 = 87 miles.

Answer: D
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