2

a) Hospital Staff want to estimate the percentage of their staff smoke tobacco. They want to be 95% confident that their estimates are within 4.5% of the true percent. How many staff members should they sample?

b) Before the recent downturn, one airline bragged that 90% of its flights were on time. A random sample of 210 flights completed this year reveals that 193 were on time. Can we conclude that the airlines on-time performance has improved? (Let a=0.10)

Ho:

HA:

Z-stat: round to 2 decimal places

P-value = Do not round

Decisin: write detain Ho or reject Ho

c) Write a summary statement for the hypothesis test in the previous problem b).