An srs of 450 450 high school seniors gained an average of ¯ x = 20 x¯=20 points in their second attempt at the sat mathematics exam. assume that the change in score has a normal distribution with standard deviation σ = 49 σ=49 . (a) find a 95 % 95% confidence interval for the mean change in score μ μ in the population of all high school seniors. (enter your answers rounded to two decimal places.)

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?