Question

Scenario 3 A comparison was made between the 100 watt light bulbs manufactured by Manufacturer 1 and those produced by Manufacturer 2. A sample of 40 bulbs from each manufacturer was taken. The bulbs were turned on and left until they burnt out and the time (in hours) was recorded. Do a hypothesis test to determine if the average life expectancy of the bulbs differs by companies. Assume unequal variances. The data is in worksheet LightBulbs. Data for Exam 1.xlsx. B Let Population 1 be Manufacturer 1

Answer 1

Answer:

To test,

$Ho:\mu 1-\mu 2=0$   

$H1:\mu 1-\mu 2\neq 0$

# Excel Output:

t-Test: Two-Sample Assuming Unequal Variances
	Manufacturer1	Manfacturer2
Mean	909.65	1018.35
Variance	8893.464103	9389.874359
Observations	40	40
Hypothesized Mean Difference	0
df	78
t Stat	-5.084307282
P(T<=t) one-tail	1.23639E-06
t Critical one-tail	1.664624645
P(T<=t) two-tail	2.47277E-06
t Critical two-tail	1.990847069

Q.13)

Test statistic= -5.084

Q.14)

P value=2.47277.10-6

Q.15)

Where p value < 0.05 ( Alpha level)

We reject Ho

Conclusion: There is difference in life expectancy of bulbs between the two companies.