Ryan went skydiving. He jumped out of the airplane at a height of 12,000 ft. His free-fall is modeled by the quadratic equation h(t) = -51t? +795t + 12,000. After free-falling for less than a minute, Ryan releases the parachute and his fall changes from a quadratic model to
a linear model: h(t) = -75t + 9000. For both models, let h(t) be Ryan's height at time t. What time did he release the parachute and how high was he?

According to a research study, parents with young children slept 6.4 hours each night last year, on average. a random sample of 18 parents with young children was surveyed and the mean amount of time per night each parent slept was 6.8. this data has a sample standard deviation of 0.9. (assume that the scores are normally distributed.) researchers conduct a one-mean hypothesis at the 5% significance level, to test if the mean amount of time parents with young children sleep per night is greater than the mean amount of time last year. the null and alternative hypotheses are h0: μ=6.4 and ha: μ> 6.4, which is a right-tailed test. the test statistic is determined to be t0=1.89 using the partial t-table below, determine the critical value(s). if there is only one critical value, leave the second answer box blank.