An analyst wants to know how many electronic devices a person owns. A survey on a random sample of 100 people is conducted and the results are shown as follows:

Number of devices.        Frequency

0                                              2

1                                            19

2                                            45

3                                            31

4                                             3

(a) Construct a 95% confidence interval for the population mean number of electronic devices own by a person.

(b) Construct a 95% confidence interval for the population proportion of people having 2 or more electronic devices.