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 |
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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). Click on Discuss to view users comments. |
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 |
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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). Click on Discuss to view users comments. |
