Can someone tell me how to solve this, i cant really understand

a farmer wishes to enclose a pasture that is bordered on one side by a river (so one of the four sides won't require fencing). she has decided to create a rectangular shape for the area, and will use barbed wire to create the enclosure. there are 600 feet of wire available for this project, and she will use all the wire. what is the maximum area that can be enclosed by the fence? (hint: use this information to create a quadratic function for the area enclosed by the fence, then find the maximum of the function.)

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.