3. There are three fire stations (A, B, and C) in the city. The average number o

Question

3. There are three fire stations (A, B, and C) in the city. The average number of calls per month at the firehouses are 33, 17 and 22, respectively. On average the number of calls per month for the city is _______? The standard deviation of the number of calls per month at the firehouses are 6, 4, and 5, respectively. What is the standard deviation of the number of calls for the city?

would the average be 33+17+22 /3? do i need to use variance for this problem? which equation to i use , thank you

Explanation / Answer

Yes, the average is the sum of calls per month divided by the number of stations.

(33 + 17 + 22)/3 = 24

The standard deviation is a little different. The general formula is:

[(V1 - )2 + (V2 - )2 + (V3 - )2 ... (Vn - )2] =

Where V is the value, is the mean (arithmetic average), and is the standard deviation.

[(33 - 24)2 + (17 - 24)2 + (22 - 24)2] =

[(9)2 + (-7)2 + (-2)2] =

[81 + 49 + 4] =

[134] =

11.576 =

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