Finding a Mean with Little Data

sharrison

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Oct 3, 2007
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Problem: On June 1, 1998, the average age of the 33 employees at Acme Cement was 47 years old. On June 1, 1999, three of the staff aged 65, 58, and 62 retired and were replaced by four employees aged 24, 31, 26, and 28. What was the average age of the employees at Acme Cement on June 1, 1999?

This is for my Statistical Apps class, and I am a bit confused. I took the average on June 1, 1998 of 47 and added that to all the new employees ages. Then, I divided that number by 34 because there are now 34 employees instead of 33 to get a grand mean of approximately 31 years old. Am I on the right track...or completely wrong :shock: ? Thanks!
 
What was the sum of the ages, as of 30 June?

After deleting the people who would not be working on 1 July, what was the sum?

After adding the people who started on 1 July, what was the sum?

Given the new total number of employees, what was the new average?

Eliz.
 
Got it! :D So, to find the total sum, I would multiply the number of employees (33) by the average (47) to get 1,551. Then, I would subtract out the retired employees ages (65, 58, and 62) to get 1,366. Next, add on the new employees (24, 31, 26, and 28) to get a sum of 1,475. To get the new average, I then divide like I had by 34, which gives me an average of approx. 43 years old. Thanks alot for your help!
 
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