Answer:
b. 2.28%.
Step-by-step explanation:
Mean temperatue (μ) = 1000°F
Standard Deviation (σ) = 50
°F
For any temperature value, X, the z-score is given by:
For X= 900°F

A z-score of -2.0 corresponds to the 2.28-th percentile of a normal distribution. Therefore, the probability that X<900 is:

Step-by-step explanation:
f(x) = x² − 6x + 9
f(½) = (½)² − 6(½) + 9
f(½) = ¼ − 3 + 9
f(½) = 6¼
The value is 6¼, or as an improper fraction, 25/4.
Solution: Let x be the height of a student in Marta's class.
The mean height of 18 students in Marta's class is 60 inches
We know that:




Therefore, the total measure of all 18 student's heights is 1080 inches