APTITUDE KNOWLEDGE NO:1

1)Out of 80 coins,one coin is counterfeit,what is the minimum number of weighing to find counterfeit coin?(Note:Counterfeit coin is lesser weight than fair coin)

a)5 or 7 b)5 or 6 c)6 or 7 d)8 or 6

Ans:(b)

Explanation:

count

First weighing 40 40 1

Second 20 20 2

Third 10 10 3

Fourth 5 5 4

Fifth 2 2 5 àTake four & weight it remaning one.

If the counterfeit coin is not present in the fifth step means weighing is equal.So the count is 5.

Otherwise

count

Sixth 1 1 6

Ans: 5 or 6

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2)In a row of 36 pupils,the first boy is followed by one girl,the second boy is folled by two girls,the third by 3 girls and so on like this.What is the number of girls in the second half of the row?

a)14 b)13 c)15 d)17

Ans:(c)

Explanation:

Total

Boy 1 1 1 1 1 1 1 1 =8

Girl 1 2 3 4 5 6 7 =28

Second half= 2+6+7=15

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3)John’s father will be twice his age 6 years from now.His mother was twice his age 2 years before.If john will be 24 from two years now.What is the difference between his fathers and mother’s age.

a)8 b)5 c)4 d)2

Ans:(a)

Explanation:

Father=F

Mother=M

F+6=2(J+6)---->(1)

M-2=2(J-2)--->(2)

J+2=24

J=22 ------------>(3)

Sub 3 in 1 and 2.Then we get

M=42

F=50

Difference is 8

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