How to find standard deviation in Casio fx cg 50

The avenues in a particular city run north to south and are numbered consecutively with 1st avenue at the western border of the city. the streets in the city run east to west and are numbered consecutively with 1st street at the southern border of the city. for a festival, the city is not allowing cars to park in a rectangular region bordered by 5th avenue to the west. 9th avenue to the east, 4th street to the south, and 6th street to the north. if x is the avenue number and yis the street number, which of the following systems describes the region in which cars are not allowed to park? 5th ave 9th ave

The length of a rectangular board is 3 feet less than twice its width. a second rectangular board is such that each of its dimensions is the reciprocal of the corresponding dimensions of the first rectangular board. if the perimeter of the second board is one-fifth the perimeter of the first, what is the perimeter of the first rectangular board?  

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?