Question 3 (1 point) A company manufacturing computer chips finds that 8% of all

Question

Question 3 (1 point) A company manufacturing computer chips finds that 8% of all chips manufactured are defective. Management is concerned that high employee turnover is partially responsible for the high defect rate. In an effort to decrease the percentage of defective chips, management decides to provide additional training to those employees hired within the last year. After training was implemented, a sample of 450 chips revealed only 27 defects. Was the additional training effective in lowering the defect rate? Which of the following statements is true about this hypothesis test? It is a two-tailed test about a proportion. It is a one-tailed test about a mean. It is a one-tailed test about a proportion. It is a two-tailed test about a mean.

Explanation / Answer

Given that,
possibile chances (x)=27
sample size(n)=450
success rate ( p )= x/n = 0.06
success probability,( po )=0.08
failure probability,( qo) = 0.92
null, Ho:p=0.08  
alternate, H1: p<0.08
level of significance, = 0.05
from standard normal table,left tailed z /2 =1.64
since our test is left-tailed
reject Ho, if zo < -1.64
we use test statistic z proportion = p-po/sqrt(poqo/n)
zo=0.06-0.08/(sqrt(0.0736)/450)
zo =-1.5639
| zo | =1.5639
critical value
the value of |z | at los 0.05% is 1.64
we got |zo| =1.564 & | z | =1.64
make decision
hence value of |zo | < | z | and here we do not reject Ho
p-value: left tail - Ha : ( p < -1.56386 ) = 0.05893
hence value of p0.05 < 0.05893,here we do not reject Ho

ANSWERS
---------------
null, Ho:p=0.08
alternate, H1: p<0.08

it is a one tailed test about the proportion

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