business statistics

posted by .

For one of the tasks in a manufacturing process, the mean time for task completion has historically been 35.0 minutes, with a standard deviation of 2.5 minutes. Workers have recently complained that the machinery used in the task is wearing out and slowing down. In response to the complaints, plant engineers have measured the time required for a sample consisting of 100 task operations. The 100 sample times, in minutes, re in data file XR09022. Using the mean for this sample, and assuming that the population standard deviation has remained unchanged at 2.5 minutes, construct the 95% confidence interval for the population mean. Is 35.0 minutes within the confidence interval? Interpret your “yes” or “no” answer in terms of whether the mean time for the task may have changed.

  • business statistics -


    CI95 = mean + or - 1.96(sd divided by √n)
    ...where + or - 1.96 represents the 95% confidence interval using a z-table, sd = standard deviation, √ = square root, and n = sample size.

    With your data:
    CI95 = mean + or - 1.96 (2.5/√100)

    Note: Determine the mean for the sample to be used in the above calculation.

    Finish the calculation and determine the interval. Determine if the 35 minutes is contained within the interval.

    I hope this will help get you started.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. math

    one task takes 7 mins second task takes 12 min third task takes 21 nin how long dids the 3 tasks take, as a fraction of a hour 7/30+12/30+21/30=40/30 =1 1/3 hr is that right?
  2. Advanced Production

    A time study od a certain service task found a average cycle time of 15 minutes, with a standard deviation of 5 minutes. These figures were based on a sample of 100 measurements. Is the sample large enough that we are 95% confident …
  3. Statistics

    If a completion time for a task is normally distributed with a mean of 15 seconds and a standard deviation of 2.5 seconds, what is the probability of getting a time less than 9.7 seconds?
  4. operation management

    A firm is planning to set up an assembly line to assemble 40 units per hour. Assume that 57 minutes per hour are productive. The time to perform each task and the tasks preceding each task are as follows: Task Preceding Task Time to …
  5. Operations management

    An appliance manufacturer wants to contract with a repair shop to handle authorized repairs. The company has an acceptable range of repair time from 50 minutes to 90 minutes. Two firms have submitted bids for the work. In the evaluation …
  6. statistics

    The time required by workers to complete an assembly job has a mean of 50 minutes and a standard deviation of 8 minutes. To spot check the workers' progress on a particular day, their supervisor intends to record the times 60 workers …
  7. statistics

    You are designing a study to determine whether music has an effect on learning. Previous research indicates that the standard deviation to learn a task is 3.4 minutes. How many subjects would you need to ensure with 90% confidence …
  8. statistics

    historically, the mean timr to complete this statistics test is 54 minutes with a standard deviation of 9 minutes. how much time should i allow, if my goal is for 95% of the students to be able to complete this test
  9. Statistics

    18 workers at a large assembly plant were asked the time it took to commute to work. The data was analyzed in Minitab and the Descriptive Statistics for the data appears below. Descriptive Statistics: Minutes Variable N Mean Median …
  10. statistics

    Times for a surgical procedure are normally distributed. There are two methods. Method A has a mean of 28 Minutes and a standard deviation of 4 minutes, while B has a mean of 32 minutes and a standard deviation of 2 minutes. a)which …

More Similar Questions