In a large​ city, 55​% of people pass the​drivers' road test. Suppose that every​ day, 400 people independently take the test. Complete parts​ (a) through​ (d) below. a. What is the number of people who are expected to​ pass? The expected number is 220. ​(Round to the nearest whole number as​needed.) b. What is the standard deviation for the number expected to​ pass? The standard deviation is 10. ​(Round to the nearest whole number as​ needed.) c. After a great many​ days, according to the Empirical​ Rule, on about​ 95% of these​ days, the number of people passing will be as low as​ _____ and as high as​ _____. (Hint: Find two standard deviations below and two standard deviations above the​ mean.) After a great many​ days, according to the Empirical​ Rule, on about​ 95% of these​ days, the number of people passing will be as low as _______and as high as _______.​(Round to the nearest whole number as​ needed

Answer :

Answer:

a) The number of people expected to pass  is 220

b) Standard deviation is 10

c) After a great many​ days, regarding the Empirical​ Rule, on about​ 95% of these​ days, the number of people passing will be as low as 200 and as high as 240.

Step-by-step explanation:

a) The number of people expected to pass = np = 400*0.55 = 220

b) Standard deviation = \sqrt{npq} = \sqrt{400*0.55*0.45} = 10

c) Regarding the empirical rule, 95% of the observations lie within 2 SD from the mean. Therefore,

Lower bound = 220 - 2*!0 = 200

Upper bound = 220 + 2*10= 240

After a great many​ days, regarding the Empirical​ Rule, on about​ 95% of these​ days, the number of people passing will be as low as 200 and as high as 240.

After a great many​ days, regarding the Empirical​ Rule, on about​ 95% of these​ days, the number of people passing will be as low as 200 and as high as 240.

It is given that

55 % of people pass the ​drivers' road test and  400 people independently take the test.

So, the number of people who are expected to pass = 400*0.55 = 220

What is the standard deviation formula for binomial distribution?

Standard deviation is the square root of variance i.e [tex]\sqrt{npq}[/tex]

Where n is no of trials while p and q are complementary probabilities.

Standard deviation =[tex]\sqrt{400*0.55*0.45}[/tex] = [tex]\sqrt{99}[/tex] =9.95≈10

Two standard deviation below the mean = 220-2*10 =200

Two standard deviation above the mean= 220 + 2*10= 240

Therefore, After a great many​ days, regarding the Empirical​ Rule, on about​ 95% of these​ days, the number of people passing will be as low as 200 and as high as 240.

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