Each of three charities in Novel Grove Estates has 8 persons serving on its board of directors. If exactly 4 persons serve on 3 boards each and each pair of charities has 5 persons in common on their boards of directors, then how many distinct persons serve on one or more boards of directors?
A.
B.
C.
D.
E.
Options:
(A) 8
(B) 13
(C) 16
(D) 24
(E) 27
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Each group has 8 = 8+8+8 = 24 max
4 people are in 2 groups, subtract 4 people twice as they are counted twice
Each pair of groups has 5 in common, so in addition to the 4 people subtract 1 from each group
Ans: 8+8+8-(2(4)) - 3 = 13 So the answer is: (B).
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A boy runs 200 metres in 24 seconds. What is his speed ?
Options:
(A) 20 km/hr
(B) 24 km/hr
(C) 28.5 km/hr
(D) 30 km/hr
(E) 35 km/hr
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200/24 * 18/5 = 30 km/hr So the answer is: (D).
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How many two-digit numbers satisfy this property.: The last digit (unit's digit) of the square of the two-digit number is 8 ?
Options:
(A) 1
(B) 2
(C) 3
(D) 4
(E) none of these
--
A number ending in 8 can never be a perfect squar So the answer is: (E).
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