heart rates normally distributed

Question

heart rates normally distributed mean of 68 beats per minute, standard deviation of 2 beats per minute. If 500 women are​ examined, how many would you expect to have a heart rate of less than 69 ​?

Answer 1

z = (x - µ)/σ where x = 69, μ = 68 and σ = 2

z = (69-68)/2 = 0.5

On the z table (Std. Normal Distribution) the area to the left of a z of 0.5 on the curve is 0.8413.

Therefore 84.1% of women would be expected to have a heartbeat of less than 69.

84.1% of 500 is ≈ 420

Answer 2

Without a table (or calculator) the number would be between 250 and 421.

Are choices provided?

z = 0.5

percentage is 69.15

346.75 would be the number of women