Lee la siguiente información. En una olimpiada matemática, cada estudiante recibe un punto por cada pregunta acertada que tenga, en la siguiente tabla de frecuencias se muestra la clasificación de la cantidad de estudiantes de acuerdo con su puntaje obtenido.

De acuerdo con la tabla, ¿cuál es aproximadamente la desviación estándar?
A.
6,12
B.
7
C.
8,42
D.
9

X+y=-4 x-y=2 use elimination with adding and subtraction

You're locked out of your house. the only open window is on the second floor, 25 feet above the ground. there are bushes along the edge of the house, so you will need to place the ladder 10 feet from the house. what length ladder do you need to reach the window?

The survey of study habits and attitudes (ssha) is a psychological test that measures the motivation, attitude toward school, and study habits of students, scores range from 0 to 200. the mean score for u. s. college students is about 115, and the standard deviation is about 30. a teacher who suspects that older students have better attitudes toward school gives the ssha to 55 students who are at least 30 years of age. the mean score is 113.2. assume the population standard deviation is 30 for older students what is the margin of error for a 95% confidence interval for the population mean score for a. older students? b. compute the 95% confidence interval for the population mean score for older students. c. compute the 99% confidence interval for the population mean score for older students. d. compute the 88% confidence interval for the population mean score for older students.