Question

Chest circumferences of adult males are known to follow a Normal distribution with mean 40 inches and standard deviation 21 inches Suppose we collect a random sample of 78 adult males. What is the probability that the average chest circumference of this group will be exactly 40.03 inches? Select one: O a We cannot answer this question with the information given. O b. 0.8365 c. 0.0000 d. 0.9800 e. O 1635

Answer 1

we have given :

n = sample size = 78

μ = population mean = 40

σ = population standard deviation = 2.1

what is the probability that the average chest circumference of this group will be exactly 40.03 ?

Answer : here answer is = 0.000

correct option is C

here we can say x follow normal distribution that is it is continous distribution , and range of x is continous ,

then sample mean is also normal distribution ,

we know that rule we can not find probability for continous random variable at equal

point or probability for equal value .  

ie P [x = c ] = 0 here same thing P [ x̄ = 40.03 ] = 0 ,