Answer:
He invested 3,000 at 7% and 4,000 at 9%.
Step-by-step explanation:
From the information given, you can write the following equations:
x+y=7,000 (1)
0.07x+0.09y=570 (2)
You can solve for x in (1)
x=7,000-y (3)
Now, you can replace (3) in (1) and solve for "y":
0.07(7,000-y)+0.09y=570
490-0.07y+0.09y=570
0.02y=80
y=80/0.02
y=4,000
Finally, you can replace the value of "y" in (3):
x=7,000-4,000
x=3,000
According to this, the answer is that he invested 3,000 at 7% and 4,000 at 9%.
Answer:
It would be D, 62
Step-by-step explanation:
The sample size for the group with the average height is the highest, being at 40 instead of 30, 20, or 10, and therefore has the most accurate average height.
Answer:
This statement can be made with a level of confidence of 97.72%.
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 8.1 mm
Standard Deviation, σ = 0.5 mm
Sample size, n = 100
We are given that the distribution of thickness is a bell shaped distribution that is a normal distribution.
Formula:
Standard error due to sampling:

P(mean thickness is less than 8.2 mm)
P(x < 8.2)
Calculation the value from standard normal z table, we have,

This statement can be made with a level of confidence of 97.72%.