Question

the times of all 15 year olds who run a certain race are approximately normally distributed with a given mean

Answer 1

The percentage of the runners who have times less than 14.4 sec is  0.15%

The times of all 15-year old who run a certain race are approximately normally distributed with a given mean of 18 sec and a standard deviation of 1.2 sec.

We know that,

where,

X = raw score = 14.4

μ = mean = 18

σ = standard deviation = 1.2

Putting the values,

Finding the probability from the z score table, we get

P(z < -3) = 0.00135 = 0.135%

Disclaimer: The question is incomplete. Please read below to find the missing content.

Question: The times of all 15-year-olds who run a certain race are approximately normally distributed with a given mean of 026-1 = 18 seconds and a standard deviation of 026-2. = 1.2 sec. What percentage of the runners have times less than 14.4 seconds?

0.15%

0.15%

0.30%

0.60%

2.50%

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