Answer:
Step-by-step explanation:
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:
x=9,-1 and
Explanation:
we have been given with the quadratic equation
we compare the given quadratic equation with general quadratic equation
general quadratic is
from given quadratic equation a=1,b= -8,c= -9
substituting these values in the formula for discriminant
Now, to find the value of x
Formula is
Now, substituting the values we will get
And rewritting the given equation by shifting 9 to right hand side of the given equation and taking minus inside the bracket so as to convert it in the form of
Answer:
C) 5 3√2
Step-by-step explanation:
<u>L</u><u>a</u><u>w</u><u> </u><u>o</u><u>f</u><u> </u><u>E</u><u>x</u><u>p</u><u>o</u><u>n</u><u>e</u><u>n</u><u>t</u>
Compare the terms.
Therefore, a = -2 and n = 3. From the law of exponent above, we receive:
<u>E</u><u>x</u><u>p</u><u>o</u><u>n</u><u>e</u><u>n</u><u>t</u><u> </u><u>D</u><u>e</u><u>f</u><u>.</u> (For cubic)
Factor (-2)^3 out.
(-2) • (-2) = 4 | Negative × Negative = Positive.
4 • (-2) = -8 | Negative Multiply Positive = Negative.
If either denominator or numerator is in negative, it is the best to write in the middle or between numerator and denominators.
Hence,
The answer is - 1 / 8