The Apple Company wants to investigate the defect rate of iPhones. So, Apple tests every 10th phone off the production line. Is this a biased or unbiased way to test phones
biased, because they aren't testing each phone
unbiased, because they are randomly choosing every 10th phone
biased, because they are only testing Apple phones
unbiased, because they need to make sure phones are working

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?