We have to solve for m:

m can take any value as this equation is an identity.
9>y
Thats it.....
Do you need something else or just that?
Answer:
And if we solve for a we got
And the limits for this case are: (214.4; 295.4)
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the annual precipitation of a population, and for this case we know the distribution for X is given by:
Where
and
The confidence level is 95.44 and the signficance is
and the value of
. And the critical value for this case is 
Using this condition we can find the limits
And if we solve for a we got
And the limits for this case are: (214.4; 295.4)
Say you were solving 27 + 19. If you were planning on using the friendly numbers strategy, you'd look at the first <span>addend, 27, and determine that</span> the closest "friendly number" here is thirty, which you'd get by adding 3. From there, you can jump to the next friendly number, forty, by adding another 10. So far you'd've added 13, and you'd need another 6 for that too add up to 19, your second addend. After adding 3, 10, and 6 to 27, you'd find your sum, or "final answer"- 46.
I hope this was what you were looking for!