question archive Using technology, use the normal approximation to find the indicated probability

Using technology, use the normal approximation to find the indicated probability

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Using technology, use the normal approximation to find the indicated probability. The sample size is n, the population proportion of successes is p, and X is the number of successes in the sample.

n = 104, p = 0.7: P(65 ≤ X ≤ 77)

Question 13 options:

A: 0.1573

B: 0.0379

C: 0.8049

D: 0.8427

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According to the question,

 

Given,

 

n = 104

p = 0.7

 

p = Probability of success

q = 1 - p = 0.3

 

μ = Mean

= np

= 104 * 0.7

= 72.8

 

σ2 = Variance

= npq

= 104 * 0.7 * 0.3

σ2 = 21.84

σ = 4.6733

 

To find P(65 ≤ X ≤ 77)

 

= P[65 - 72.8 / 4.6733 < X - 72.8 / 4.6733 < 77 - 72.8 / 4.6733]

 

= P[-7.8 / 4.6733 < Z < 4.2 / 4.6733]

 

= P[-1.6690 < Z < 0.8987]

 

= P[Z < 0.90] - P[-1.67]

 

= 0.8389 - 0.0367

 

= 0.8022

 

≈ 0.8049