Complete question:
The manager of a supermarket would like to determine the amount of time that customers wait in a check-out line. He randomly selects 45 customers and records the amount of time from the moment they stand in the back of a line until the moment the cashier scans their first item. He calculates the mean and standard deviation of this sample to be barx = 4.2 minutes and s = 2.0 minutes. If appropriate, find a 90% confidence interval for the true mean time (in minutes) that customers at this supermarket wait in a check-out line
Answer:
(3.699, 4.701)
Step-by-step explanation:
Given:
Sample size, n = 45
Sample mean, x' = 4.2
Standard deviation 
= 2.0
Required:
Find a 90% CI for true mean time
First find standard error using the formula:
Standard error = 0.298
Degrees of freedom, df = n - 1 = 45 - 1 = 44
To find t at 90% CI,df = 44:
Level of Significance α= 100% - 90% = 10% = 0.10
Find margin of error using the formula:
M.E = S.E * t
M.E = 0.298 * 1.6802
M.E = 0.500938 ≈ 0.5009
Margin of error = 0.5009
Thus, 90% CI = sample mean ± Margin of error
Lower limit = 4.2 - 0.5009 = 3.699
Upper limit = 4.2 + 0.5009 = 4.7009 ≈ 4.701
Confidence Interval = (3.699, 4.701)
Answer:
h(t) = -16t2 + 144
h(1) = -16(12) + 144 = 128 ft
h(2) = -16(22) + 144 = 80 ft
h(2) - h(1) = 80 - 128 = -48 ft
It fell 48 ft between t = 1 and t = 2 seconds.
It reaches the ground when h(t) = 0
0 = -16t2 + 144
t = √(144/16) s = 3s
It reaches the ground 3s after being dropped.
Step-by-step explanation:
The required point-slope form of the equation of the line is y - 5 = -4(x + 1).
Given that, To determine an equation in point-slope form for the line that passes through the point with the given slope. point: (-1, 5) and m=-4.
What is the slope of the line?
The slope of the line is a tangent angle made by line with horizontal. i.e. m =tanx where x in degrees.
Here,
The point-slope of the equation of the line is given by,
y - y₁ = m(x - x₁)
Put the values in the above equation of the line
y - 5 = -4 (x - (-1))
y - 5 = -4 (x + 1)
Thus, the required point-slope form of the equation of the line is y - 5 = -4(x + 1).
Learn more about slopes visit:
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Answer:
x = 10.75
Step-by-step explanation:
4(x+9)=8x-7
Step 1: Distribute the 4 to the x and 9
4 * x = 4x
4 * 9 = 36
We now have 4x + 36 = 8x - 7
Step 2: add 7 to both sides
36 + 7 = 43
-7 + 7 cancels out
We now have 4x + 43 = 8x
Step 3 subtract 4x from both sides
4x - 4x cancels out
8x - 4x = 4x
We now have 4x = 43
step 4 divide both sides by 4
4x / 4 ( the 4s cancel out and we're left with x )
43/4 = 10.75
We're left with x = 10.75
Answer:
99
Step-by-step explanation:
