No matter how I approach it..i don't get it!

A recent study of 25 students reported that they spend an average of $18.53 per week on gas. The standard deviation of the sample was $3.00. Find the 95% confidence interval of the true mean.

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- August 12th 2010, 05:13 AMMahoganybeauty06Complety lost on stastics problem!
No matter how I approach it..i don't get it!

A recent study of 25 students reported that they spend an average of $18.53 per week on gas. The standard deviation of the sample was $3.00. Find the 95% confidence interval of the true mean. - August 12th 2010, 05:43 AMmr fantastic
The formula you need can be found here: Confidence Intervals

The formula will also be in your class notes and textbook. Please show what you've tried and say where you get stuck. - August 12th 2010, 05:50 AMArchie Meade
By the Central Limit Theorem

where is the population SD, is the population mean, is the sample size,

is the sample mean and is the sample SD.

The 95% interval ranges from 2.5% to 97.5%.

Locate the Z-score for 97.5% and use the values given to rearrange the equation for