please check and show work :-0 25)a safety officer wants to prove that the avera
ID: 2950358 • Letter: P
Question
please check and show work :-0
25)a safety officer wants to prove that the average of cardsdriven by a school is less than 25 mph. suppose that a randomsample of 14 cards shows an average speed of 24.0 mph, with asample standard deviation of 2.2 mph. assume that the speeds ofcars are normally distributed. use =.05
A. what are the appropriate null and alternative hypotheses?
a. h0: µ=25 and hA: µ<25
b. h0: µ=25 and hA: µ>25
c. h0: µ=25 and hA: µ185
d. h0: µ25 and hA: µ=25
B. what is the value of the test statistic?
a. -1.80
b. -1.70
c. -1.50
d. none of the above
C. report your conclusion
a. the results are statistically significant so that the averagespeed>25 mph
b. the results are statistically significant so that the averagespeed<25 mph
c. there is not enough evidence to conclude average speed<25mph
d. none of the above
he wants to prove (that's a claim) < 25
it has to be Ha which never has an equal sign
Ho which always has an =, must be Ho:µ=25
a. h0: µ=25 and hA: µ<25
when claim has < (or >) it's a one tail test
with = it's 2-tail.
since direction is <, it's a left tail test (negativecutoff)
n=14 cars is not enough to use a z-score
use a t-score with n-1=14-1=13 degrees of freedom
and =.05 . The t scores table shows a cutoff of -1.771
Area to left of -1.771 is 'reject Ho'
area to right of -1.771 is 'do not reject Ho'
the test statistic is t=(xbar-mu)/(s/sqrt(n))
t=(24-25)/(2.2/sqrt(14)
t=-1/0.588=-1.70
conclusion
Since test stat is in DO NOT REJECT region
we do not reject ho that µ=25 and'
c. there is not enough evidence to conclude average speed<25mph
The mean of the sample was less than 25 but not enough less tosupport the claim.
Explanation / Answer
25)a safety officer wants to prove that the average of cardsdriven by a school is less than 25 mph. suppose that a randomsample of 14 cards shows an average speed of 24.0 mph, with asample standard deviation of 2.2 mph. assume that the speeds ofcars are normally distributed. use =.05
A. what are the appropriate null and alternative hypotheses?
a. h0: µ=25 and hA:µ<25
b. h0: µ=25 and hA: µ>25
c. h0: µ=25 and hA: µ185
d. h0: µ25 and hA: µ=25
B. what is the value of the test statistic?
a. -1.80
b. -1.70
c.-1.50
d. none of the above
C. report your conclusion
a. the results are statistically significant so that the averagespeed>25 mph
b. the results are statistically significant so that the averagespeed<25 mph
c. there is not enoughevidence to conclude average speed<25 mph
d. none of the above
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