Suppose a normal distribution has a mean of 38 and a standard deviation of 2. What is the probability that a data value is between 37 and 41? Round your answer to the nearest tenth of a percent.

A. 83.5%
B. 77.5%
C. 56.5%
D. 62.5%

Question

Suppose a normal distribution has a mean of 38 and a standard deviation of 2. What is the probability that a data value is between 37 and 41? Round your answer to the nearest tenth of a percent.

 		A.	83.5%
 		B.	77.5%
 		C.	56.5%
 		D.	62.5%

amistre64 · Answer

i wanna say that 62 is the most reasonable to me

anonymous · Answer

thank you,did you get my message ?

amistre64 · Answer

yeah

anonymous · Answer

what do you think

amistre64 · Answer

post them up and lets see what we can do

anonymous · Answer

If a normal distribution has a mean of 44 and a standard deviation of 8, what is the z-score for a value of 50?

 		A.	0.75
 		B.	1.25
 		C.	1.75
 		D.	0.25

amistre64 · Answer

$$z=\frac{x-mean}{sd}$$

anonymous · Answer

so where would i plug the 44 in

amistre64 · Answer

mean is 44
sd is 8
and x = 50

anonymous · Answer

so i got 6/8

amistre64 · Answer

correct

anonymous · Answer

which simplified is 3/4

anonymous · Answer

which is .75 :D

anonymous · Answer

If a normal distribution has a mean of 132 and a standard deviation of 20, what is the value that has a z-score of 3.6?

 		A.	168
 		B.	180
 		C.	144
 		D.	204

amistre64 · Answer

which value is 3.6 sds from the mean?

132 + 3.6(20)

anonymous · Answer

i got like 2000 something :(

amistre64 · Answer

try to hit the decimal ....

anonymous · Answer

lol sorry i saw that its 204 ! are you a teacher ?

anonymous · Answer

Which of the following expressions entered into a graphing calculator will return the probability that a data value in a normal distribution is between a z-score of -2.33 and a z-score of 0.17?

 		A.	normalcdf(-0.17, 2.33)
 		B.	normalcdf(0.17, 2.33)
 		C.	normalcdf(-2.33, 0.17)
 		D.	normalcdf(2.33, 0.17)

amistre64 · Answer

im an old person, im working on a masters in math tho

anonymous · Answer

I hope you get it,your very smart

amistre64 · Answer

the normalCDF functionon a ti83 takes the parameters:

low, high, mean, sd

amistre64 · Answer

it defaults to mean=0 and sd=1

anonymous · Answer

k you lost me :)

amistre64 · Answer

they give you 2 values to input .... one of them is lower in value than the other; how would you suggest we input them?

anonymous · Answer

im sorry i dont know,these z-scores are gibberish to me :/

amistre64 · Answer

what are the zscores they give us?

anonymous · Answer

-2.33 and 0.17

amistre64 · Answer

and the input into the normalCDF function is (low,high)

would you agree that in this case, a negative value is always lower than a positive value?

anonymous · Answer

yes ! :)

amistre64 · Answer

so armed with this vast assortment of low high trivia, do you see a best option?  :)

anonymous · Answer

so it would be a,-0.17 and 2.33 ?

amistre64 · Answer

im going to assume that is in jest ... and agree with C

anonymous · Answer

haha your funny and make everything so simple !

anonymous · Answer

If the mean of a normal distribution is 26, what is the median of the distribution?

 		A.	18
 		B.	22
 		C.	14
 		D.	26

amistre64 · Answer

in a normal distribution, mean=mode=median

anonymous · Answer

so it stays 26 ?

anonymous · Answer

its a trick question ?

amistre64 · Answer

its a conceptual question :)  they assume you know a normal distibution as equality among the central tendencies

anonymous · Answer

hmmm translate please :)

anonymous · Answer

and i just have 4 more if thats ok

amistre64 · Answer

the most observed value of the data is at the highest point
the middle value (median), since its symmetric, is in the middle
the mean of a symettric shape is the middle ...

mean = mode = median

anonymous · Answer

In a normal distribution, what percentage of the data falls within 1 standard deviation of the mean?

 		A.	99.7%
 		B.	34%
 		C.	95%
 		D.	68%

amistre64 · Answer

A and C are obvoius absurdities

the question is, what do they mean by 1sd of the mean?

ill assume they want 1 sd to each side of the mean and go with 68

anonymous · Answer

sweet !

anonymous · Answer

Suppose the heights of the members of a population follow a normal distribution. If the mean height of the population is 68 inches and the standard deviation is 4 inches, 99.7% of the population will have a height within which of the following ranges?

 		A.	60 inches to 76 inches
 		B.	56 inches to 80 inches
 		C.	52 inches to 84 inches
 		D.	64 inches to 72 inches

amistre64 · Answer

the emprical rule, 1-2-3
                        68-95-99

so take your mean and subtract 3sds for the lower limit
take your mean and add 3sds for the upper limit

anonymous · Answer

im confused again,about this whole thing and 3 sds and all that

amistre64 · Answer

sd is shorthand for standard deviation

they give you the mean and the sd values

anonymous · Answer

still kind of lost but im thinking d?

amistre64 · Answer

not d

mean + 3(sd)

they give you a mean of 68 and an sd of 4

anonymous · Answer

ahhhh so b :)

amistre64 · Answer

b is better yes :)

anonymous · Answer

Suppose a normal distribution has a mean of 98 and a standard deviation of 6. What is P(x  104)?

 		A.	0.16
 		B.	0.84
 		C.	0.025
 		D.	0.975

amistre64 · Answer

is that x < 104?

anonymous · Answer

yes

amistre64 · Answer

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