CA Foundation · Quantitative Aptitude · Theoretical Distributions
The daily sales of a Lucknow sweet shop are normally distributed with mean Rs 8,000 and standard deviation Rs 1,000. Given P(0 < Z < 1) = 0.3413 and P(0 < Z < 2) = 0.4772, what is the probability that daily sales lie between Rs 7,000 and Rs 10,000?
The probability is 0.8185. The limits convert to Z = -1 and Z = 2, on opposite sides of the mean, so the table areas add: 0.3413 + 0.4772 = 0.8185.
- A0.8185Correct
- B0.6826
- C0.1359
- D0.9544
Explanation
Z for 7000 = -1 and for 10000 = 2. Probability = P(-1<Z<0) + P(0<Z<2) = 0.3413 + 0.4772 = 0.8185. Option 0.1359 wrongly subtracts the areas (0.4772 - 0.3413) as though both limits were on the same side.
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