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by kvcpk » Wed Jul 14, 2010 9:54 am
pullagurla wrote:15625^1/2=125 then 15625^1/2 + 156.25^1/2 +1.5625^1/2
a. 1.3875
b. 13.875
c. 138.75
d. 1387.5
e. 13875
125+12.5+1.25 [Because decimal of two points in square is equal to 1 point in original]
=138.75

pick C
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by Gurpinder » Wed Jul 14, 2010 12:32 pm
you can easily ballpark this question.

15625^1/2=125 ---- is just saying that the square root of 15625 is 125.

since you are going to have to add some more values to this value, you can get rid of answer choices A & B because they are too small.

15625^1/2 + 156.25^1/2 +1.5625^1/2

the square root of the bolded #'s will not be larger than 125 because the #'s are small.

so there is no way your answer can go from 125 straight to the thousands (answer choices d,e). So the only credited response is 138.75.

= )
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by Rahul@gurome » Wed Jul 14, 2010 5:14 pm
156.25^1/2 = (15625/100)^1/2 = 15625^1/2 / 10 = 125/10 = 12.5
1.5625^1/2 = (15625/10000)^1/2 = 15625^1/2 / 100 = 125/100 = 1.25

Therefore, 15625^1/2 + 156.25^1/2 +1.5625^1/2 = 125 + 12.5 + 1.25 = 138.75

The correct answer is (C).
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