Simply square roots of negative numbers

You are in charge of the customer service phone line with many employees. at the end of each phone callthe customers are asked to rate their service from 1 to 5 stars, with 5 being the best. you find the averagerating for 20 randomly selected employees and decide you want to improve the ratings so you require thoseemployees to go through a new training program. you then wait a week and find the new average rating foreach employee. the average change is an increase in 1.3 stars with a standard devation of .9 stars.(a) is this data paired or not paired? (b) what are the null and alternative hypothesis being tested? (c) what is the t-statistic you would use? write the general formula and the final calculation.(d) sketch a t-distribution, label your t-statistic and the probability you would be interested in:

El piloto de un avión observa la pista de aterrizaje del aeropuerto de chiclayo con un ángulo de depresión de 30°; avanza 600 metros y el nuevo ángulo con qie se observa la pisga de aterrizaje es de 60°. ? a qué altura se encuentra volando el avión?

If the circumference of the circle is below 72, what is the length of ab (the minor arc)