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Kaifbinarshad
Only option 1 is sufficient and option 2 is not sufficient alone.

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No both are alone sufficient.
1st - Given temp for range Mon - Thurs as 87
But, We know temp for whole given rage Mon - Fri = 86
So from this Friday = (86*5) - (4*87) = 82

2nd - Lets assume rest of the days has x avg and for y for friday.
Statement says, The high temperature on Friday reduced the average high temperature for the five-day period by 1 degree Fahrenheit.
Now as per statement given lets form equation.
\(\frac{4x + y }{ 5} = x-1\)
we have value for x-1 = 86 that makes x=87
Solve and get the value for y it will be same as we got in Statement 1.
Hence Sufficient.

Answer is D.
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(M+Tu+W+Th+F)/5=86

statement 1 alone : (M+Tu+W+Th)/4=87 so M+Tu+W+Th=87*4 ie F=86*5-87*4 sufficeient
satetement 2 alone: without the high temperature on Friday, the average would have been (M+Tu+W+Th)/4=86+1 sama as statement 1 sufficient

Answer D
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Still do not understand why B is sufficient. The questions stem says "the average (arithmetic mean) high temperature was 86 degrees Fahrenheit". Why without the high temperature on Friday, the average would have been (M+Tu+W+Th)/4=86+1?

Abdelaali91
(M+Tu+W+Th+F)/5=86

statement 1 alone : (M+Tu+W+Th)/4=87 so M+Tu+W+Th=87*4 ie F=86*5-87*4 sufficeient
satetement 2 alone: without the high temperature on Friday, the average would have been (M+Tu+W+Th)/4=86+1 sama as statement 1 sufficient

Answer D
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Still do not understand why B is sufficient. The questions stem says "the average (arithmetic mean) high temperature was 86 degrees Fahrenheit". Why without the high temperature on Friday, the average would have been (M+Tu+W+Th)/4=86+1?

Abdelaali91
During a five-day period, Monday through Friday, the average (arithmetic mean) high temperature was 86 degrees Fahrenheit. What was the high temperature on Friday?

(1) The average high temperature for Monday through Thursday was 87 degrees Fahrenheit.

(2) The high temperature on Friday reduced the average high temperature for the five-day period by 1 degree Fahrenheit.

(M+Tu+W+Th+F)/5=86

statement 1 alone : (M+Tu+W+Th)/4=87 so M+Tu+W+Th=87*4 ie F=86*5-87*4 sufficeient
satetement 2 alone: without the high temperature on Friday, the average would have been (M+Tu+W+Th)/4=86+1 sama as statement 1 sufficient

Answer D

Stem says the sum of the temperatures for (total for 4 days) + (Friday) = 86 * 5.

(2) states that the average for the 4 days was 87, so the total for the 4 days is 87 * 4.

Thus, 87 * 4 + (Friday) = 86 * 5, giving Friday = 82.
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