Answer:
a) 0.71
b) 0.9863
Step-by-step explanation:
a. Given the mean prices of a house is $403,000 and the standard deviation is $278,000
-The probability the probability that the selected house is valued at less than $500,000 is obtained by summing the frequencies of prices below $500,000:
![P(X](https://tex.z-dn.net/?f=P%28X%3C500%2C000%29%3DP%28X%3D0%29%2BP%28X%3D500%29%5C%5C%5C%5C%3D0.34%2B0.37%5C%5C%5C%5C%3D0.71)
Hence, the probability of a house price below $500,000 is 0.71
b. -Let X be the mean price of a randomly selected house.
-Since the sample size 40 is greater than 30, we assume normal distribution.
-The probability can therefore be calculated as follows:
![P(X](https://tex.z-dn.net/?f=P%28X%3Cx%29%3DP%28z%3C%5Cfrac%7B%5Cbar%20X-%5Cmu%7D%7B%5Csigma%2F%5Csqrt%7Bn%7D%7D%29%5C%5C%5C%5CP%28X%3C500%2C000%29%3DP%28z%3C%5Cfrac%7B500-403%7D%7B278%2F%5Csqrt%7B40%7D%7D%29%5C%5C%5C%5C%3DP%28z%3C2.2068%29%5C%5C%5C%5C%5C%5C%3D0.9863)
Thus, the probability that the mean value of the 40 houses is less than $500,000 is 0.9863