Question

In analyzing hits by B bombers Targets are subdivided to 465 regions each an area of .02 km2. A total of 411 bombs hit the combined area 465. A) If the region is randomly selected what is the probability that the same region has been hit twice? b) What is the probability a target has been hit three times

7- In analyzing hits by B bombers Targets are subdivided to 465 regions each an area of .02 km2. A total of 411 bombs hit the combined area 465. A) If the region is randomly selected what is the probability that the same region has been hit twice? b) What is the probability a target has been hit three times.

Answer 1

Solution:

Givendata:

In analyzing hits by B bombers Targets are subdivided to 465 regions each an area of .02 km2.

Given,

p = 1/465

sample n = 411

Mean = np

= 411/465

= 0.8839

Standard deviation = sqrt(npq) = sqrt(411*1/465(1- 1/465)) = 0.9391

a)

X = 2

z = (x - u)/s

substitute values

= (2 - 0.8839)/0.9391

= 1.1885

P(z < = 1.1885) = 0.8826818 [since from z table]

= 0.8827

b)

X = 3

P(z < (3 - 0.8839)/0.9391) = P(z < 2.25)

= 0.9877755 [since from z table]

= 0.9878

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