1
NDA Mathematics 18 April 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
The mean of 12 observations is 75. If two observation are discarded, then the mean of the remaining observations is 65. What is the mean of the discarded observations?
A
250
B
125
C
120
D
Cannot be determined due to insufficient data
2
NDA Mathematics 18 April 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
If k is one of the roots of the equation x(x + 1) + 1 = 0, then what is its other root?
A
1
B
-k
C
k2
D
-k2
3
NDA Mathematics 18 April 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
The geometric mean of a set of observations is computed as 10. The geometric mean obtained when each observations xi is replaced by $\rm 3x_i^4$ is
A
810
B
900
C
30000
D
81000
4
NDA Mathematics 18 April 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language

If $\rm P(A\cup B)=\dfrac{5}{6}, P(A\cap B)=\dfrac{1}{3}\:and\:P(\bar A)=\dfrac{1}{2}$, then which of the following is/are correct?

1. A and B are independent events.

2. A and B are mutually exclusive events.

Select the correct answer using the code given below.

A
1 only
B
2 only
C
Both 1 and 2
D
Neither 1 nor 2
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