Researchers are investigating whether taking aspirin regularly reduces the risk of heart attacks. Four hundred men
participate in the study. The men are divided randomly into two groups: one group takes aspirin pills, and the other group
takes placebo pills (a pill with no aspirin in it). The men each take one pill a day, and they do not know which group they are
in. At the end of the study, researchers will count the number of men in each group who have had heart attacks.

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?