29. operating System Market Share. NetMarketShare.com reported that, in 2014, the market share for the desktop operating system market was as follows.
| Windows 7 | Windows XP | Windows 8 | Others |
|---|---|---|---|
| 51% | 25% | 13% | 11% |
A survey this year of 10,000 randomly selected desktop operating system had the following results.
| Windows 7 | Windows XP | Windows 8 | Others |
|---|---|---|---|
| 4500 | 1500 | 2000 | 2000 |
Test whether the population proportions have changed since 2014, using level of significance .
11.1.29
, , , .
: The random variable does not follow the distribution specified in . Checking the conditions, the expected frequencies are , , , , Because none of these expected frequencies is less than one, and none of the expected frequencies is less than five, the conditions for performing the goodness of ft test are met. . Reject if . . Compare with is . Therefore, we reject . There is evidence that the variable operating system does not follow the distribution specified in . In other words, there is evidence that the desktop operating systems market share has changed.