Answer:
The baby must weigh approximately 8.31 pounds.
Explanation:
We are given the following information in the question:
Mean, μ = 7.5 pounds
Standard Deviation, σ = 1.2 pounds
We are given that the distribution of weights of newborn babies is a bell shaped distribution that is a normal distribution.
Formula:

We have to find the third quartile or

We have to find the value of x such that the probability is 0.75
Calculation the value from standard normal z table, we have,
Thus, the baby must weigh approximately 8.31 pounds.