An important feature of digital cameras is battery? life, thenumber of shots that can be taken before the battery needs to berecharged. The accompanying data contains battery life informationfor 29 subcompact cameras and 16 compact cameras. Complete parts?(a) through? (d) below.
Battery life data for the two types of digital camera:
Subcompact Compact
302 394
310 445
289 447
279 260
246 345
197 239
326 332
242 221
276 233
236 256
197 281
223 397
279 507
209 201
261 148
221 129
236
209
208
289
162
276
197
141
232
222
198
168
149
a. Is there evidence of a difference in thevariability of the battery life between the two types of digital?cameras? (Use
alpha?equals=0.05?.)
What are the correct null and alternative? hypotheses?
What is the test? statistic?
?(Round to two decimal places as? needed.)
What is the critical? value? Select the correct choice below andfill in the answer box within your choice.
?(Round to two decimal places as? needed.)
A.
Upper F Subscript alphaF?equals=...
B.
Upper F Subscript alpha divided by 2F?/2equals=...
What is the correct? conclusion?
A.
Reject
Upper H 0H0.
There is insufficient evidence of a difference in thevariability of the battery life between the two types of digitalcameras.
B.
Do not reject
Upper H 0H0.
There is insufficient evidence of a difference in thevariability of the battery life between the two types of digitalcameras.
C.
Reject
Upper H 0H0.
There is sufficient evidence of a difference in the variabilityof the battery life between the two types of digital cameras.
D.
Do not reject
Upper H 0H0.
There is sufficient evidence of a difference in the variabilityof the battery life between the two types of digital cameras.
b. Determine the? p-value in? (a) and interpretits meaning.
The? p-value in part? (a) is.....
?(Round to three decimal places as? needed.)
What does the? p-value mean?
A.
The probability of obtaining a sample that yields a teststatistic equal to or more extreme than the one in? (a) is equal tothe? p-value if there is a difference in the two populationvariances.
B.
The probability of obtaining a sample that yields a teststatistic equal to or more extreme than the one in? (a) is equal tothe? p-value if there is no difference in the two populationvariances.
C.
The probability of obtaining a sample that yields a teststatistic equal to or less extreme than the one in? (a) is equal tothe? p-value if there is no difference in the two populationvariances.
D.
The probability of obtaining a sample that yields a teststatistic equal to or less extreme than the one in? (a) is equal tothe? p-value if there is a difference in the two populationvariances.
c. What assumption about the populationdistribution of the two types of cameras is necessary in? (a)?
A.
The populations have equal means.
B.
The populations are the same size.
C.
The populations have different means.
D.
The populations are normally distributed.
Is this assumption? satisfied?
?
Yes,
No,
because
?
the subcompact sample is
the compact sample is
the two samples are
the compact sample mean is
?
left-skewed.
right-skewed.
smaller than the subcompact sample.
roughly symmetric.
skewed in opposite directions.
smaller than the subcompact sample mean.
equal to the subcompact sample mean.
equal to the subcompact sample.
larger than the subcompact sample mean.
larger than the subcompact sample.
d. Based on the results of? (a), which t testshould be used to compare the mean battery life of the two typesof? cameras?
A.
The? pooled-variance t test should be? used, because the twopopulations have equal variances.
B.
The? separate-variance t test should be? used, because the twopopulations do not have equal variances.
C.
The? separate-variance t test should be? used, because the twopopulations have equal variances.
D.
The? pooled-variance t test should be? used, because the twopopulations do not have equal variances.
