Swaziland has the highest hiv prevalence in the world : 25.9% of this country’s population is infected with hiv. the elisa test is one of the first and most accurate tests for hiv. for those who carry hiv, the elisa test is 99.7% accurate. for those who do not carry hiv, the elisa test is 92.6% accurate. 1. if an individual from swaziland has tested positive, what is the probability that he carries hiv ? 2. if an individual from swaziland has tested negative, what is the probability that he is hiv free ?

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?