<span>A medical researcher wants to investigate the amount of time it takes for patients' headache pain to be relieved after taking a new prescription painkiller. She plans to use statistical methods to estimate the mean of the population of relief times. She believes that the population is normally distributed with a standard deviation of 18 minutes. How large a sample should she take to estimate the mean time to within 4 minutes with 97% confidence?
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n = [z*s/E]^2
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n = [2.17*18/4]^2 = 96 when rounded up
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Answer:
Equation 1: 7x + 2y = 12.8
Equation 2: 6x + 3y = 12
Cost of 1 apple: $1.60
Cost of 1 orange: $0.80
Cost of 1 orange: $Step-by-step explanation:
Let's use the elimination method to solve this
Multiply equation 1 by 3
(7x + 2y = 12.8) x 3 = 21x + 6y = 38.4
Multiply equation 2 by -2
(6x + 3y = 12) x -2 = -12x - 6y = -24
The x terms will cancel each other out
21x + 6y = 38.4
-12x - 6y = -24
9x = 14.4
Divide by sides by 9 to isolate the x variable
9x/9 = 14.4/9
x = 1.6
This means an apple costs $1.60
Plug the new x into one of the original equations to find y; we'll use equation 1
7(1.6) + 2y = 12.8
11.2 + 2y = 12.8
Subtract 11.2 from both sides
11.2 + 2y = 12.8
- 11.2 - 11.2
2y = 1.6
Divide both sides by 2
2y/2 = 1.6/2
y = 0.8
This means an orange costs $0.80
Tyler moved 180 kilograms
30-12=18 so 18×2=36 36×5=180