To decide whether or not to purchase a new hand held laser scanner for use in inventory stock, test
are conducted on the scanner currently in use and on the new scanner. The data are obtained on the
number of 7 – inch bar codes that can be scanned per second:
New Old
n1 = 61
xÌ…1 = 40
s1
2 = 24.9
n1 = 61
xÌ…1 = 29
s1
2 = 22.7
i) Test H0: σ1
2 = σ2
2
at the α = 0.2 level to be sure that pooling is appropriate
ii) Find sp
2
iii) Find a 90% confidence interval on μ1 − μ2
iv) Does the new laser appear to read more bar codes per second on average? Explain
To decide whether or not to purchase a new hand held laser scanner for use in inventory stock, test
are conducted on the scanner currently in use and on the new scanner. The data are obtained on the
number of 7 – inch bar codes that can be scanned per second:
New Old
n1 = 61
xÌ…1 = 40
s1
2 = 24.9
n1 = 61
xÌ…1 = 29
s1
2 = 22.7
i) Test H0: σ1
2 = σ2
2
at the α = 0.2 level to be sure that pooling is appropriate
ii) Find sp
2
iii) Find a 90% confidence interval on μ1 − μ2
iv) Does the new laser appear to read more bar codes per second on average? Explain
