# CBSE 11TH MATHEMATICS (Test 1)

Tag: cbse 11th mathematics
Q.1
Two dice are thrown. The number of sample points in the sample space when 6 does not appear on either dice is
A. 18
B. 11
C. 25
D. 30
Explaination / Solution:

total no. of outcomes=62=36

The pair which shows 6 on either dice are {(6,1),(6,2),(6,3),(6,4),(6,5),(1,6),(2,6),(3,6),(4,6),(5,6),(6,6)}=11

So total number of sample points in sample space when 6 on either dice do not appear=36-11=25

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Q.2
From a pack of 52 cards, the cards are drawn one by one till an ace appears. The chance that an ace does not come up in first 26 cards is
A. None of these
B. 23/ 27
C. 109/ 153
D. 46/ 153
Explaination / Solution:
No Explaination.

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Q.3
If  and  are two independent events, then P  is equal to
A. P(E1)+P(E2)+P(E1+E2)
B. P(E1)P(E2)
C. None of these
D. P(E1) +(E2)
Explaination / Solution:
No Explaination.

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Q.4
The probability that a man will live for 10 more years is  and that his wife will live 10 more years is. The probability that neither will be alive in 10 years is
A. 12
B. 1112
C. 512
D. 712
Explaination / Solution:
No Explaination.

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Q.5
A coin tail on both sides is tossed twice. The probability of getting ‘a head’ is
A. 1
B. 3/4
C. 1/2
D. 0
Explaination / Solution:
No Explaination.

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Q.6
If the letters of the word ‘ INDEPENDENCE ‘ are written down at random in a row , then the chance that no two E’s occur together is
A. 14/ 55
B. 1/ 55
C. None of these
D. 54/ 55
Explaination / Solution:
No Explaination.

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Q.7
Coefficient of correlation between the observations ( 1, 6 ) , ( 2 , 5 ) , ( 3 , 4) , ( 4 , 3 ) , ( 5 , 2 ) , ( 6 , 1 ) is
A. -1
B. 0
C. 1
D. None of these
Explaination / Solution:

use,r(x,y)=1ni=1n(XiX¯)(YiY¯)1ni=1n(XiX¯)21ni=1n(YiY¯)2
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Q.8
The mean weight of a group of 10 items is 28 and that of another group of n items is 35.The mean of combined group of 10 + n items is found to be 30. The value of n is
A. 4
B. 2
C. 10
D. 12
Explaination / Solution:

sum of weights of 10 items =280

sum of weights of n items = 35n

so, sum of weights of ( 10 + n) items = 280 + 35n

so ,mean = (280 + 35 n) / ( 10 + n)

30(10 + n ) = 280 + 35n

solving we get, n = 4

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Q.9
The mean of the first n terms of the A.P. (a + d ) + ( a + 3d ) + ( a + 5d ) +………..is
A. (a+nd)/2
B. a + nd
C. a+n2d
D. a+n2d
Explaination / Solution:

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Q.10
ρ(X,Y) is equal to
A. COV(X,Y)VAR(X)VAR(Y)
B. COV(X,Y)
C. cov(x,y)/sd
D.