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eLitmus Probability questions for eLitmus exam | eLitmus Questions for pH Test

21

Three dices are thrown what is d probability to get atleast one six?

A.

91/616

B.

91/216

C.

91/256

D.

91/215

See Answer & Explanation Lets Discuss
Correct answer is : B
Explanation

The probabilty of getting no other than six is =(5/6)*(5/6)*(5/6)=125/216
now probabiilty of getting atleast 1 six is= 1-probabilty of getting no six at all
=> 1-125/216
=91/216

 
22

Suppose p is the number of cars per minute passing through a certain road junction between 5 PM and 6 PM, and p has a Poisson distribution with mean 3. What is the probability of observing fewer than 3 cars during any given minute in this interval?

A.

8 / (2e3)

B.

9 / (2e3)

C.

17 / (2e3)

D.

26 / (2e3)

See Answer & Explanation Lets Discuss
Correct answer is : C
Explanation

PR(X < 3) = Pr(x = 0) + Pr(x = 1) + Pr(x = 2)
= f(0, 3) + f(1, 3) + f(2, 3)
Put \lambda = 3 and k = 0, 1, 2 in the formula

\!f(k; \lambda)= \Pr(X=k)= \frac{\lambda^k e^{-\lambda}}{k!},

we get=17 / (2e3)

 
23

Out of all the 2-digit integers between 1 and 100, a 2-digit number has to be selected at random. What is the probability that the selected number is not divisible by 7?

A.

13/90

B.

12/90

C.

78/90

D.

77/90

See Answer & Explanation Lets Discuss
Correct answer is : D
Explanation

There are total 90 two digit numbers between 1 to 100, out of them 13 are divisible by 7

so, 90-13=77

=>77/90

 
24

Suppose a fair six-sided die is rolled once. If the value on the die is 1, 2, or 3, the die is rolled a second time. What is the probability that the sum total of values that turn up is at least 6?

A.

10/21

B.

5/12

C.

2/3

D.

1/6

See Answer & Explanation Lets Discuss
Correct answer is : B
Explanation

The following are different possibilities for which the sum total of values that turn up is at least 6:-

(1,5) (1,6) (2,4) (2,5) (2,6) (3,3) (3,4) (3,5) (3,6)

So total probability is 9/36 + 1/6(1/6 probability that first time 6 is rolled) = 15/36 = 5/12.

 
25

If two fair coins are flipped and at least one of the outcomes is known to be a head, what is the probability that both outcomes are heads?

A.

1/3

B.

1/4

C.

1/2

D.

2/3

See Answer & Explanation Lets Discuss
Correct answer is : A
Explanation

There are only three possibilities {h, t}, {h, h}, {t, h}; since we know one outcome is head, 

so, the probability of both heads = 1/3.

 
 

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