Question

The true length of recovery for patients with knee surgery is normally distributed with a mean of 123 days and a standard deviation of 1 day. What proportion of the patients will recover between 121 and 124 days?

Answer 1

0.81859

Explanation:

Given that the length of recovery days for patients with knee surgery is normally distributed with :

Mean, μ = 123 days

Standard deviation, σ = 1 day

The proportion of patients that will recover with 121 and 124 days :

We obtain the Probability of Z score :

Z = (x - μ) / σ

P(Z < (x - μ) / σ) < Z < P(Z < (x - μ) / σ)

P(Z < (121 - 123) / 1) < Z < P(Z < (124 - 123) / 1)

P(Z < - 2) < Z < P(Z < 1)

Using the normal distribution table :

P(Z < 1) - P(Z < - 2)

0.84134 - 0.02275

= 0.81859