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Course: AP??/College Statistics?>?Unit 11
Lesson 3: Carrying out a test for a population mean- When to use z or t statistics in significance tests
- Example calculating t statistic for a test about a mean
- Calculating the test statistic in a t test for a mean
- Using TI calculator for P-value from t statistic
- Using a table to estimate P-value from t statistic
- Calculating the P-value in a t test for a mean
- Comparing P-value from t statistic to significance level
- Making conclusions in a t test for a mean
- Free response example: Significance test for a mean
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Making conclusions in a t test for a mean
Problem
A local pizza store knows the mean amount of time it takes them to deliver an order is minutes after the order is placed. The manager came up with a new system for processing delivery orders, and they were curious if it changed the mean delivery time. They took a sample of delivery orders to test minutes versus minutes, where is the mean delivery time under the new system.
The delivery times in the sample had a mean of minutes and a standard deviation of minutes. These results produced a test statistic of and a P-value of approximately . Assume that the conditions for inference were met.
Is there sufficient evidence at the level to conclude that the mean delivery time has changed from minutes?