Answer:
Q6. D
Q8. A
Step-by-step explanation:
Q6. In 40 trials, he flipped '2 heads and 1 tail' 16 times.
For 2 heads, probability= 16/40= 4/10
For 120 trials, number of times= 4/10 × 120= 48
Q8.
Answer is A because the inequality shows that x is equal or greater than 8 so the dot at 8 has to be coloured.
Note that we do not change the inequality sign unless we are dividing the whole thing by -1.
Let be the population mean lifetime of circulated $1 bills.
By considering the given information , we have :-
Since the alternative hypotheses is two tailed so the test is a two tailed test.
We assume that the lifetime of circulated $1 bills is normally distributed.
Given : Sample size : n=50 , which is greater than 30 .
It means the sample is large so we use z-test.
Sample mean :
Standard deviation :
Test statistic for population mean :-
The p-value=
Since the p-value (0.0433834) is greater than the significance level (0.02) , so we do not reject the null hypothesis.
Hence, we conclude that we do not have enough evidence to support the alternative hypothesis that the average lifetime of a circulated $1 bill differs from 18 months.