
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= 1probabilty of getting no six at all => 1125/216 =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 = 3 and k = 0, 1, 2 in the formula
we get=17 / (2e^{3})
23 
Out of all the 2digit integers between 1 and 100, a 2digit 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, 9013=77
=>77/90
24 
Suppose a fair sixsided 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
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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.
