Math Problem 2! Help Appreciated

[Dunzo]

Hey guys! I have a problem of the week for my math class I haven't really looked at it but if you all could help it would be greatly appreciated! If you agree with one person's answer please post saying so. Thanks!

September Rainfall:
The mean September rainfall in Washington, D.C., during a 30-year period is 3.79 inches. Suppose that this September is unusually rainy. How much rainfall would be required to increase the mean by a minimum of 0.02 inches?

[HavokD]

Oh well here I go:

A mean is the sum of n values, divided by n. In this case we have a mean of 30 years, which can be written as:

mean= sum / 30 = 3.79

In here, sum= 113.7

Where sum is the total sum of each year's inches of rain. Now, we want the mean to go up to 3.81 (an increase of 0.02). That yields:

sum/ 31= 3.81

And in here, sum= 118.11

Bear in mind we are dividing by 31 because we are counting another year.

So, we need to know that extra value, which should be above the average (so it increases the mean by 0.02 inches).

All we gotta do is take our second sum, and substract the first sum, that will mean we are substracting 31 different values for the next year less 30 values from the actual 30 years, that substraction will give us one value, which is the value of the 31th year:

118.11-113.7= 4.41 inches

Feel free to correct me, and thanks, I hope you understood it well.

[Dunzo]

thanks havokd (: ill have a new one next week! :p

[HavokD]

No problem xD keep en coming :P

[LostraC]

No problem xD keep en coming :P

I'll keep cumming. :cool: