Incomes of employees in an industrial concern are given below. The total income of the 10 employees in the class over $ 2500 is $ 30,000. Income ($) Frequency Below 500 90 500-1000 150 1000-1500 100 1500-2000 80 2000-2500 70 2500 and over 10 (a) Compute the arithmetic mean income. (b) Every employee belonging to the top 25% of the earners is required to pay 5% of his/her income to the workers' relief fund. Estimate the contribution to this fund.