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amanda cheng

amanda c.

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Statistics Test Scores Tests in the author's statistics classes have scores with a standard deviation equal to $14.1$. One of his last classes had 27 test scores with a standard deviation of 9.3. Use a $0.01$ significance level to test the claim that this class has less variation than other past classes. Does a lower standard deviation suggest that this last class is doing better?

Statistics Test Scores Tests in the author's statistics classes have scores with a standard deviation equal to $14.1$. One of his last classes had 27 test scores with a standard deviation of 9.3. Use a $0.01$ significance level to test the claim that this class has less variation than other past classes. Does a lower standard deviation suggest that this last class is doing better?

Essentials of Statistics

Hypothesis Testing

Testing a Claim About a Standard…
The amount of time that a drive-through bank teller spends on a customer is a random variable with a mean $\mu=3.2$ minutes and a standard deviation $\sigma=1.6$ minutes. If a random sample of 64 customers is observed, find the probability that their mean time at the teller's counter is (a) at most 2.7 minutes: (b) more than 3.5 minutes; (c) at least 3.2 minutes but less than 3.4 minutes.

The amount of time that a drive-through bank teller spends on a customer is a random variable with a mean $\mu=3.2$ minutes and a standard deviation $\sigma=1.6$ minutes. If a random sample of 64 customers is observed, find the probability that their mean time at the teller's counter is (a) at most 2.7 minutes: (b) more than 3.5 minutes; (c) at least 3.2 minutes but less than 3.4 minutes.

Probability and Statistics for Engineers and Scientists

Fundamental Sampling Distributions and…

Sampling Distribution of Means
The amount of time that a customer spends waiting at an airport check-in counter is a random variable with mean 8.2 minutes and standard deviation 1.5 minutes. Suppose that a random sample of $n=49$ customers is observed. Find the probability that the average time waiting in line for these customers is (a) Less than 10 minutes (b) Between 5 and 10 minutes (c) Less than 6 minutes

The amount of time that a customer spends waiting at an airport check-in counter is a random variable with mean 8.2 minutes and standard deviation 1.5 minutes. Suppose that a random sample of $n=49$ customers is observed. Find the probability that the average time waiting in line for these customers is (a) Less than 10 minutes (b) Between 5 and 10 minutes (c) Less than 6 minutes

Applied Statistics and Probability for Engineers

Sampling Distributions and Point…

Sampling Distributions and the Central…
The MacBurger restaurant chain claims that the waiting time of customers for service is normally distributed, with a mean of 3 minutes and a standard deviation of 1 minute. The quality-assurance department found in a sample of 50 customers at the Warren Road MacBurger that the mean waiting time was 2.75 minutes. At the .05 significance level, can we conclude that the mean waiting time is less than 3 minutes?

The MacBurger restaurant chain claims that the waiting time of customers for service is normally distributed, with a mean of 3 minutes and a standard deviation of 1 minute. The quality-assurance department found in a sample of 50 customers at the Warren Road MacBurger that the mean waiting time was 2.75 minutes. At the .05 significance level, can we conclude that the mean waiting time is less than 3 minutes?

Basic Statistics for Business and Economics

Questions asked

ANSWERED

Brent Burkett verified

Numerade educator

A survey found that the monthly phone bill is $63 for an average user and $77 for users that uses premier package. Assuming that the monthly phone bills for both users follow a normal distribution with a standard deviation of $7, find the probability; a. That an average user's phone bill is less than $70 per month. b. A user of premier package is able to keep his phone bill less than $85 per month. c. An advance package user pays bill $70 to $83.

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Ivan Kochetkov verified

Numerade educator

A random variable X has a normal distribution with a mean of 300 and a standard deviation of 5. Find the value of each the following. a) P(X < 315). b) P(295 < X < 309). c) P(X > 310). A random variable X has a normal distribution with a mean of 45 and a standard deviation of 7. Find the value of each the following. i) P(X > 50). ii) P(40 < X < 55). iii) P(X < 35).

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Donna Densmore verified

Numerade educator

Consider the following frequency table. egin{tabular}{|c|c|c|c|} hline Class & Frequency & egin{tabular}{c} Cumulative \ frequency end{tabular} & egin{tabular}{c} Upper-class \ boundary end{tabular} \ hline ( 30-34 ) & 3 & & \ hline ( 35-39 ) & 6 & & \ hline ( 40-44 ) & 18 & & \ hline ( 45-49 ) & 12 & & \ hline ( 50-54 ) & 7 & & \ hline ( 55-59 ) & 4 & & \ hline & ( sum f=50 ) & & \ hline end{tabular} a) Given that ( sum f x=2,230 ) and ( sum f x^{2}=101,470 ), determine the variance for this frequency table. b) Draw an ogive based on the frequency table.

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Robin Corrigan verified

Numerade educator

A survey of students' favourite after-school activities was conducted at a school. Table 1 shows the results of this survey. Table 1 egin{tabular}{|l|c|c|l|} hline Activity & egin{tabular}{c} Number of \ Students end{tabular} & egin{tabular}{c} Relative \ Frequency end{tabular} & egin{tabular}{c} Cumulative \ Frequency end{tabular} \ hline Play Sports & 45 & & \ hline Talk on Phone & 53 & & \ hline Visit With Friends & 99 & & \ hline Earn Money & 44 & & \ hline Chat Online & 66 & & \ hline end{tabular} i. Based on the table above, draw a bar chart to represent the data. (5 Marks) ii. Copy and complete the table. (5 Marks)

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ANSWERED

Lynn Larson verified

Numerade educator

As an owner of a cafeteria, Jack wants to determine whether the population mean waiting time to place an order has changed in the past year from its previous population mean value of 4.5 minutes. From past experience, he can assume that the population is normally distributed, with a population standard deviation of 1.2 minutes. Jack select a sample of 25 orders during one-hour period and found mean for the samples is 5.1 minutes. a) Write the null and alternative hypothesis for this problem. b) What is the critical value for this test at α = 0.05? Sketch a diagram showing the rejection region for the critical value. c) Calculate the test statistics for this problem.

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ANSWERED

T. L. verified

Numerade educator

A market trader sells ball-point pens at his stall. He sells pens for a different fixed price in each of six weeks. He notes the number of pens that he sells in each of these weeks. The results are shown in the following table. egin{tabular}{|l|c|c|c|c|c|c|} hline Price (RM) & 10 & 15 & 20 & 25 & 30 & 25 \ hline egin{tabular}{l} Number of \ pen (Unit) end{tabular} & 68 & 60 & 55 & 48 & 38 & 32 \ hline end{tabular} a) Identify the dependent ( ( mathrm{y}) ) and independent variable ( ( mathrm{x} ) ). (2 Marks) b) Calculate the correlation of coefficient, ( r ). Interpret the result. (4 Marks) c) Find the regression line. (4 Marks)

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Aparna Shakti verified

Numerade educator

Suppose a student observes on six different samples of temperature readings (in degrees Celsius); 102.5, 101.7, 103.1, 100.9, 100.5, and 102.2. If he knows that the standard deviation (population) for this procedure is 1.2 degrees, what is the confidence interval for the population mean at a 95% confidence level?

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ANSWERED

Aparna Shakti verified

Numerade educator

a) A normal distribution has a mean of 20 and a standard deviation of 2. i. Compute the probability of a value less than 20 hours. ii. Compute the probability of a value that is less than 23.2 hours. iii. Compute the probability of a value that is greater than 22.8 hours.

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ANSWERED

Aparna Shakti verified

Numerade educator

The following table shows a random sample of 100 hikers and the areas of hiking preferred: egin{tabular}{|l|c|c|c|c|} hline Gender & Coastline & egin{tabular}{c} Near lake \ and Streams end{tabular} & egin{tabular}{c} On Mountain \ Peaks end{tabular} & Total \ hline Female & 18 & 16 & ( a ) & 45 \ hline Male & ( b ) & ( c ) & 14 & 55 \ hline Total & ( d ) & 41 & ( e ) & ( f ) \ hline end{tabular} i. What is the value for ( a, b, c, d, e ) and ( f ) ? (2 Marks) ii. What is the probability of selecting a hiker that preferred near lake and streams? (2 Marks) iii. What is the probability of selecting a male hiker or a hiker that preferred on mountain peaks? (2 Marks) iv. What is the probability of selecting a female hiker and a hiker that preferred the coastline? (2 Marks) v. What is the probability of selecting a male hiker given that he preferred near lake and streams? (2 Marks)

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Kari Hasz verified

Numerade educator

OTHERS 17° Car A Car B Car C 167°

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