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प्रश्न
The mortality rate for a certain disease is 7 in 1000. What is the probability for just 2 deaths on account of this disease in a group of 400? [Given e–2.8 = 0.06]
उत्तर
Since the mortality rate for a certain disease in 7 in loop
∴ p = `7/1000` and n = 400
The value of mean A = λp
= `400 xx 7/1000`
∴ λ = 2.8
Let x be a random variable following distribution with p(x) = `("e"^(-lambda)lambda^x)/(x!)`
∴ The distribution is P(X = 2) = `("e"^(-2 - 8) (2.8)^2)/(2!)`
= `(0.06 xx 7.84)/2`
= 0.2352
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