SOLUTION: I am having trouble understanding "at most" and "at least" If, for example, the problem was " ... Their times are normally distributed with a mean of 184 minutes and a standard

Algebra.Com
Question 624015: I am having trouble understanding "at most" and "at least"
If, for example, the problem was " ... Their times are normally distributed with a mean of 184 minutes and a standard deviation of 55 minutes. For a randomly selected person from the control group, find the probability that the time is at least 210 minutes."
I used the following function on my TI-84:
2ND, VARS, normalcdf(209.5,1E99,184,55)
=0.321454
=32.14%
is this correct?
Thanks for your time.
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!
 

Hi

for at least 210, using 209.5 is the correct spproach

 z = (209.5 - 184)/25 = .4636 which results in  .6786  or 67.86% to the left

Note: we know as 210 >184 that this P has to be greater than 50% for 

Also as to Your P(x≥210) =  Note (1-.3214) = .6786

_____________________________________________________________________________

Important to Understand z -values as they relate to the Standard Normal curve:

Below:  z = 0, z = ± 1, z= ±2 , z= ±3 are plotted.  

Note: z = 0 (x value the mean) 50% of the area under the curve is to the left and %50 to the right



 

RELATED QUESTIONS


I am having trouble coming up with equation expression for this problem, lol...  It's... (answered by ankor@dixie-net.com,MathTherapy)

Paul pays $3 every time he acts at home and $8 every time he eats out. If Paul has $200... (answered by solver91311,josgarithmetic)

I am having some trouble with understanding binomial distributions, I hope someone could... (answered by stanbon)

I am having problems understanding parabola grafting.  Example, if I am given a problem... (answered by checkley71,stanbon)

Hi Can someone please check my work?  I am having trouble understanding confidence... (answered by ewatrrr)

Hello, I am having trouble understanding and solving this problem:

Leyla wants to buy... (answered by josgarithmetic)

At a garage sale all books were one price, and all magazines were another price.  Harriet  (answered by stanbon)

I'm having trouble understanding how to write equations that relate x and y. For example,  (answered by oscargut,MathLover1)

My question has been stumping me for ever now. There are two supplementary angles. One... (answered by Mathtut,solver91311)