2. The mean is an average. After all things considered are added together, you then divide by the number of things that were considered. In this instance, you need to do the reverse. 90 is the average; now multiply by 4 (90 * 4).

3. How many months are there in a year? Multiply that number by the average rainfall for each month.

mean = [x1+ x2+x3…+xN] / N

Or, for simplicity’s sake here, mean = sum / (number of terms)

M = S/N

1). Mean= Unknown. Sum=the sum of the squares of the first ten counting numbers. Number of terms = 10.

M = [1² + 2² + 3² +4² +5² +6² +7² +8² +9² +10²]/10

= [1+4+9+16+25+36+49+64+81+100]/10

= [5+25+25+85+145+100]/10

=[55+230+100]/10

=385/10 = 38.5

2. This time, we have the mean (90) and the number of terms (4), and need the sum (S) we divided.

M=S/N: Substitute in known values

90 = S/4: Multiply through by 4 to get rid of the division

360 = S

3. Mean=3.4. Number of Terms = number of months in a year (12). Sum = Total rain

M=S/N

3.4 = S/12

S=40.8 inches

You know how to square a number, right?

What are the first ten counting numbers?

1^2 + 2^2 + 3^2 +….+10^2 = X

x/count (which is 10 here) = the mean

mean = x/count, so 90 = x/4

mean = x/count, so 3.4 = x/12

1+4+9+16+25+36+49+64+81+100

now just divide the sum by the amount of numbers, whatever that all equals, divided by 10

2. ok, for this one the problem is essentially (a+b+c+d) divided by 4 which equalls 90. so you take 90 and multiply it by 4 and that is your answer

3. well, there are only 12 months in a year, so you would take 3.4 and multiply it by 12. i think that that is your answer…..

(im less sure about this one)

hope that i could help. 🙂

1. (1+4+9+16+25+36+49+64+81+100)= 285/10= 28.5

2. 360

3. 40.8

Mean is the average of a group of numbers

#1. 1,4,9,16,25,36,49,64,81,100 which would make the mean 38.3

#2 would be 360

#3 3.4 x 12=40.8

2. 270

3. 40.8