Maths · Probability: Probability of an event, addition and multiplication theorems of probability
is a Normally distributed variable with mean and standard deviation Find \)
\( X \) is a Normally distributed variable with mean \( =30 \) and standard deviation \( =4 . \) Find \( P(x<40) \)
- A. 0 .9789
- B. 0.9938
- C. 0.9838
- D. 0.9538
Step-by-step solution
First, convert to standard normal: z = (40-30)/4 = 2.5. Then P(X<40) = P(Z<2.5). From standard normal distribution table, the cumulative probability for z=2.5 is approximately 0.9938.
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