on a certain day, the rate at which material is deposited at a recycling center is modeled by the function r, where r t( ) is measured in tons per hour and t is the number of hours since the center opened. using a trapezoidal sum with the three subintervals indicated by the data in the table, what is the approximate number of tons of material deposited in the first 9 hours since the center opened? (a) 68 (b) 70.5 (c) 85 (d) 136
