Problem Solving

hey all


can you tell me how to solve this

tanya prepared 4 different letters to be sent to 4 different addresses. For each letter she prepared envelopes with right address. if the 4 letters are put into the 4 envelopes at random, what is the probability that only one letter will be put into the correct address envelope.

a) 1/24

b) 1/4


c) 1/8

d) 1/3

e) 3/8
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5 pieces of wood have an average length of 124cm and median of 140 cm. what is the max possible length of the shortest piece.

a) 90

b) 140

c) 110

d) 130

e) 100
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3) Amy's grade was 90th percentile of the 80 grades for her class. of the 100 grades from other class, 19 were higher than any and others lower. if no grade was same as amy, then amy's grade was what percentile of grades of two classes combined.

72

80

81

85

92


thanks

harsha