A survey of nonprofit organizations showed that online fundraising has increased in the past year. Based on a random sample of 50 nonprofits, the mean one-time gift donation in the past year was $29, with a standard deviation of $10. Complete parts a and b below. a. Construct a 90% confidence interval estimate for the population one-time gift donation. 28.91 sus 29.09 (Type integers or decimals rounded to two decimal places as needed.)