Gray, Inc., a private foundation, reports the following items of income and deductions.

Interest income

$ 29,000

Rent income

61,000

Dividend income

15,000

Royalty income

22,000

Unrelated business income

80,000

Rent expenses

(26,000)

Unrelated business expenses

(12,000)

Gray is not an exempt operating foundation, and it is not eligible for the 1% tax rate.

a. Calculate the net investment income.

b. Calculate the tax on net investment income.

c. What is the purpose of the tax on net investment income?