Answer:
To find the probability of a value between 50 and 70 in a normal distribution with mean 40 and standard deviation 15, we need to first standardize the values using the z-score formula:
z = (x - μ) / σ
where x is the value we are interested in, μ is the mean, and σ is the standard deviation.
For the lower bound of 50:
z = (50 - 40) / 15 = 0.67
For the upper bound of 70:
z = (70 - 40) / 15 = 2
Using a standard normal distribution table or a calculator with a built-in normal distribution function, we can find the probabilities corresponding to these z-scores:
P(0 < z < 0.67) = 0.2514
P(0 < z < 2) = 0.4772
To find the probability of a value between 50 and 70, we can subtract the probability of the lower bound from the probability of the upper bound:
P(50 < x < 70) = P(0 < z < 2) - P(0 < z < 0.67)
P(50 < x < 70) = 0.4772 - 0.2514
P(50 < x < 70) = 0.2258
Therefore, the probability of a value between 50 and 70 in this normal distribution is 0.2258 or about 22.58%.