A package delivery service wants to compare the proportion of on-time deliveries for two of its...

A package delivery service wants to compare the proportion of on-time deliveries for two of its major service areas. In City A, 377 out of a random sample of 449 deliveries were on time. A random sample of 282 deliveries in City B showed that 220 were on time.

Compute a 99% confidence interval for the difference ?̂ ?????−?̂ ?????

Solutions

Expert Solution

We have given,

x1=377
n1=449

x2=220
n2=282

Level of significance =   0.01
Z critical value (by using Z table)=2.576
Estimate for sample proportion 1

Estimate for sample proportion 2

Confidence interval formula is


=(-0.0181,0.1371)


Lower limit for confidence interval=-0.0181

Upper limit for confidence interval is=   0.1371

orchestra answered 1 year ago

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