2. The resting pulse rates were recorded for 16 boys in gym class
before they exercised. The line plot here shows the results.
X
X
X
Х
X
Х
X
Х
X
X
X
X
X
Х
X
X
79
80
81
82
83
84
85
a.
What is the range of the pulse rates?
b. How many boys had a pulse rate over 81?
c. How many boys had a pulse rate of 83?

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.