Answer:
95% Confidence interval: (111.02,112.98)
Step-by-step explanation:
Average = 112 seconds
Standard Deviation = 9 seconds
n = 324
Confidence interval:
Putting the values, we get,
If the two triangles are similar you can use a proportion to solve for the length of the legs.

=

Now, you would cross multiply to get
4x=18
Now, you simplify that using the division property of equality.
You end up with
x=4.5
Therefore, the legs of the triangle with a base of 9 inches will each be 4.5 units long.