Question

An investigator compares the durability of two different compounds used in the manufacture of a certain automobile brake lining. A sample of 259 brakes using Compound 1 yields an average brake life of 31,495 miles. A sample of 297 brakes using Compound 2 yields an average brake life of 41,15241,152 miles. Assume that the population standard deviation for Compound 1 is 1446 miles, while the population standard deviation for Compound 2 is 4520 miles. Determine the 99% confidence interval for the true difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2.

Step 2 of 3 :

Calculate the margin of error of a confidence interval for the difference between the two population means. Round your answer to six decimal places.

Step 3 of 3:

Construct the 99% confidence interval. Round your answers to the nearest whole number. (lower and upper endpoint)

Answer #1

An investigator compares the durability of two different
compounds used in the manufacture of a certain automobile brake
lining. A sample of 260 brakes using Compound 1 yields an average
brake life of 32,023 miles. A sample of 297 brakes using Compound 2
yields an average brake life of 39,570 miles. Assume that the
population standard deviation for Compound 1 is 2395 miles, while
the population standard deviation for Compound 2 is 1673 miles.
Determine the 80% confidence interval for...

An investigator compares the durability of two different
compounds used in the manufacture of a certain automobile brake
lining. A sample of 263 brakes using Compound 1 yields an average
brake life of 41,270 miles. A sample of 291 brakes using Compound 2
yields an average brake life of 40,579 miles. Assume that the
population standard deviation for Compound 1 is 4540 miles, while
the population standard deviation for Compound 2 is 2990 miles.
Determine the 90% confidence interval for...

An investigator compares the durability of two different
compounds used in the manufacture of a certain automobile brake
lining. A sample of 121 brakes using Compound 1
yields an average brake life of 39,122 miles.
A sample of 163 brakes using Compound 2 yields an
average brake life of 48,271 miles. Assume that
the population standard deviation for Compound 1 is 3175
miles, while the population standard deviation for
Compound 2 is 1335 miles. Determine the 98%
confidence interval for...

An investigator compares the durability of two different
compounds used in the manufacture of a certain automobile brake
lining. A sample of 124 brakes using Compound 1 yields an average
brake life of 40,704 miles. A sample of 163 brakes using Compound 2
yields an average brake life of 43,525 miles. Assume that the
population standard deviation for Compound 1 is 2022 miles, while
the population standard deviation for Compound 2 is 4792 miles.
Determine the 90% confidence interval for...

An investigator compares the durability of two different
compounds used in the manufacture of a certain automobile brake
lining. A sample of 236 brakes using Compound 1 yields an average
brake life of 48,737 miles. A sample of 190 brakes using Compound 2
yields an average brake life of 49,740 miles. Assume that the
population standard deviation for Compound 1 is 4106 miles, while
the population standard deviation for Compound 2 is 1104 miles.
Determine the 80% confidence interval for...

An investigator compares the durability a two
different compounds used in the manufacture of a certain automobile
brake lining. A sample of 212 brakes using compound 1 yields an
average break life of 47895 miles. A sample of 180 brakes using
compound 2 yields an average brake life of 49767 miles. Assume that
the population standard deviation for compound 1 is 1590 miles,
while the population standard deviation for compound 2 is 4152
miles. Determine the 90% confidence interval for...

A researcher compares the effectiveness of two different
instructional methods for teaching pharmacology. A sample of 51
students using Method 1 produces a testing average of 81.6. A
sample of 76 students using Method 2 produces a testing average of
76.4. Assume that the population standard deviation for Method 1 is
12.24, while the population standard deviation for Method 2 is
11.19. Determine the 90% confidence interval for the true
difference between testing averages for students using Method 1 and...

A researcher compares the effectiveness of two different
instructional methods for teaching physiology. A sample of 189
students using Method 1 produces a testing average of 71.9. A
sample of 141 students using Method 2 produces a testing average of
78.3. Assume that the population standard deviation for Method 1 is
11.07, while the population standard deviation for Method 2 is
11.9. Determine the 98% confidence interval for the true difference
between testing averages for students using Method 1 and...

A researcher compares
the effectiveness of two different instructional methods for
teaching anatomy. A sample of 206206 students using Method
1 produces a testing average of 82.9. A sample of
244 students using Method 2 produces a testing average of
62.2. Assume that the population standard
deviation for Method 1 is 10.23, while the population standard
deviation for Method 2 is 11.35. Determine the 95% confidence
interval for the true difference between testing averages for
students using Method 1 and...

A researcher compares two compounds (1 and 2) used in the
manufacture of car tires that are designed to reduce braking
distances for SUVs equipped with the tires. The mean braking
distance for SUVs equipped with tires made with compound 1 is 55
feet, with a population standard deviation of 5.6. The mean braking
distance for SUVs equipped with tires made with compound 2 is 60
feet, with a population standard deviation of 14.2. Suppose that a
sample of 69...

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