[SOMEONE PLEASE HELP] (2x^4y^5)(-3x^2y^7)
1 answer:
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Answer:
A. Margin of error = 128.79
B. The 99% confidence interval for the population mean is (7661.21, 7918.79).
Step-by-step explanation:
We have to calculate a 99% confidence interval for the mean.
The population standard deviation is know and is σ=500.
The sample mean is M=7790.
The sample size is N=100.
As σ is known, the standard error of the mean (σM) is calculated as:
The z-value for a 99% confidence interval is z=2.576.
The margin of error (MOE) can be calculated as:
Then, the lower and upper bounds of the confidence interval are:
The 99% confidence interval for the population mean is (7661.21, 7918.79).
Answer:
B
Step-by-step explanation:
Given
7 | 3f + 4 | = 91 ← divide both sides by 7
| 3f + 4 | = 13
The absolute value function always returns a positive value, but the expression inside can be positive or negative. Thus there are 2 possible solutions.
Solve 3f + 4 = 13 → 3f = 13 - 4 = 9 ⇒ f = 3
Solve 3f + 4 = - 13 ⇒ 3f = - 13 - 4 = - 17 ⇒ f = -
As a check
Substitute these values into the left side of the equation and if equal to the right side then they are the solutions.
f = 3 : 7| 9 + 4| = 7| 13| = 7 × 13 = 91 ← True
f = -
7 | - 17 + 4| = 7| - 13| = 7 × 13 = 91 ← True
Hence the correct solutions are B