14
Q:

A box contains 100 balls, numbered from 1 to 100. If three balls are selected at random and with replacement from the box, what is the probability that the sum of the three numbers on the balls selected from the box will be odd?

A) 1/6 B) 1/3
C) 1/2 D) 1/4

Answer:   C) 1/2



Explanation:

P(odd) = P (even) =12 1(because there are 50 odd and 50 even numbers)

 

Sum or the three numbers can be odd only under the following 4 scenarios:

 

Odd + Odd + Odd = 12*12*1218

 

Odd + Even + Even = 12*12*12=18

 

Even + Odd + Even = 12*12*12=18

 

Even + Even + Odd = 12*12*12 = 18

 

Other combinations of odd and even will give even numbers. 

 

Adding up the 4 scenarios above:

 

1818+1818 = 48 = 12

Q:

X attempts 100 questions and gets 340 marks. If for every correct answer is 4 marks and wrong answer is negative one mark, then the number of questions wrongly answered by Mr. X is:

 

A) 14 B) 15
C) 12 D) 13
 
Answer & Explanation Answer: C) 12

Explanation:
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7 757
Q:

If the standard deviation of 0, 1, 2, 3 ......... 9 is K, then the standard deviation of 10, 11, 12, 13 ........... 19 will be:

 

A) K+1 B) K
C) K+4 D) K+8
 
Answer & Explanation Answer: B) K

Explanation:
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2 1275
Q:

The standard deviation of the set {10, 11, 12, 9, 8} is

A) 1 B) √2
C) 2 D) 2√2
 
Answer & Explanation Answer: B) √2

Explanation:
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8 959
Q:

Find the range of the data 2, 1, 2, 3, 5, 4, 7, 3, 5, 2, 4.

A) 5 B) 4
C) 3 D) 6
 
Answer & Explanation Answer: D) 6

Explanation:
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1 1204
Q:

Find the median, mode and mean of 9, 5, 8, 9, 9, 7, 8, 9, 8.

A) 9, 9, 9 B) 9, 8, 9
C) 8, 9, 8 D) 8, 9, 9
 
Answer & Explanation Answer: C) 8, 9, 8

Explanation:
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4 968
Q:

In the usual set notation, A  (B  C) =

 

 

A) A∪B∪A∪C B) A∩B∪A∩C
C) A∪B∩A∪C D) A∪B∩A∩C
 
Answer & Explanation Answer: C) A∪B∩A∪C

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1 3401
Q:

Find the range and mode of the data 17, 18, 28, 19, 16, 18, 17, 29, 18

A) 12 and 18 B) 13 and 18
C) 12 and 17 D) 11 and 17
 
Answer & Explanation Answer: B) 13 and 18

Explanation:
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1 1174
Q:

Find the standard deviation of {11, 7, 10,13, 9}

A) 1 B) 2
C) 4 D) 5
 
Answer & Explanation Answer: B) 2

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2 1150