Classical

Statistics and methodology - Statistics and Methodology Multiple Choice Questions

116:  

The average number of customers per minute arriving at a super bazaar is 2. Using the Poisson distribution, find the probability that during one particular minute exactly three customers will arrive

A.

0.36

B.

0.180

C.

0.120

D.

0.130

 
 

Option: B

Explanation :

Hence the answer is (b).


117:  

A coin is tossed 1000 times and head comes out 550 times. Can the deviation from expected value be due to fluctuations of simple sampling?

A.

Yes, with -1

B.

Cannot be

C.

Yes, with +1

D.

Can be

 
 

Option: B

Explanation :

Chance of getting a head p = 1/2

Expected frequency        = np = 1000 x 1/2

= 500

Standard deviation           = √(npq)

= √(1/2 x 1/2 x 1000)

= 15.81

The difference between observed frequency and expected frequency, = 550 - 500 = 50 Since the difference is greater than three times the standard error (5.81 x 3 = 47.43 <= 50) and so it cannot be accounted for by fluctuations of simple sampling.

Hence the answer is (b).


118:  

In a certain field of construction work, the wages are assumed to follow a normal distribution, with an average wage of Rs. 4 per day and a standard deviation of Rs. 0.50. If 20 workers received wages of more than Rs. 4.50 per day, what is the total number of workers?

A.

126

B.

120

C.

130

D.

190

 
 

Option: A

Explanation :

Z = (x - μ)/σ = (4.50 – 4.00)/0.50 = 1

Area to the right = 0.5 - 0.3413 = 0.1587

Therefore, the total number of workers is given by 0.1587/1.

N = 20

or      N = 20/0.1587 = 126

The total number of worker is 126.

Hence the answer is (a).




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