On May 1 Geraldo Saldana opened a savings account that paid 3.5 percent interest at Fulton Savings Bank with a deposit of $3,600. Ten days later he deposited $3,000. Fourteen days later he deposited $5,000. No other deposits or withdrawals were made. Six days later the bank calculated the daily interest. a. How much simple interest did his money earn?
b. How much was in the account at the end of the 30 days?

Aspacecraft can attain a stable orbit 300 kilometers above earth if it reaches a velocity of 7.7 kilometers per second. the formula for a rocket's maximum velocity v in kilometers per second is vequalsminus0.0098tplusc ln upper r, where t is the firing time in seconds, c is the velocity of the exhaust in kilometers per second, and r is the ratio of the mass of the rocket filled with fuel to the mass of the rocket without fuel. find the velocity of a spacecraft whose booster rocket has a mass ratio of 20, an exhaust velocity of 2.1 km/s, and a firing time of 15 s. can the spacecraft achieve a stable orbit 300 km above earth?