q: The average of Suresh's marks in English and History is 55. His average of marks in English and Science is 65. What is the difference between the marks which he obtained in History and Science?
Options:
(A) 40
(B) 60
(C) 20
(D) Data inadequate
(E) None of the above
a: E + H = (55 2) = 110;
E + S = (65 2) = 130
Reqd difference = 130 110 = 20 The answer is (C).
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q: Two pipes A and B can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?
Options:
(A) 20 hrs
(B) 22 hrs
(C) 23 hrs
(D) 24 hrs
(E) 21 hrs
a: 1/( 1/36 +1/45) = 180/9 = 20 hrs The answer is (A).
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q: Resident of town X participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and std deviation of 2 hrs. The number of hours that pat, a resident of town X, watched television last week was between 1 and 2 standard deviation below the mean. Which of the following could be the number of hours that Pat watched television last week?
Options:
(A) 30
(B) 20
(C) 18
(D) 22
(E) 6
a: 21-12 < no of hrs < 21-2
9< no of hrs < 19. The answer is (C).
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q: The average of 11 results is 40, if the average of first five results is 49 and that of the last seven is 52. Find the fifth result?
Options:
(A) 165
(B) 166
(C) 167
(D) 168
(E) 169
a:
1 to 11 = 11 * 40 = 440
1 to 5 = 5 * 49 = 245
5 to 11 = 7 * 52 = 364
5th = 245 + 364 440 = 169 The answer is (E).
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