Q1) A group of 25 internet shoppers were asked how much they spent per year on Internet. Their responses (in dollars) are shown below.
|
418
|
379
|
77
|
212
|
378
|
|
363
|
434
|
348
|
245
|
341
|
|
331
|
356
|
423
|
330
|
247
|
|
351
|
151
|
220
|
383
|
257
|
|
307
|
297
|
448
|
391
|
210
|
Determine a 95% confidence interval for mean amount spent by all Internet shoppers
Suppose that average annual salary for worker in United States is $31,000 and that annual salaries for Americans are normally distributed with standard deviation equal to $7,500. Determine the following:
a) What percentage of Americans earn below $20,000?
b) What percentage of Americans earn above $45,000?