# statistics, question 1, grade 10

26/06/2016

1)

A teacher examined 25 students in math and gave the results arranged in the following table:

 grades (xi) 10 13 15 18 20 total frequency (ni) 3 x y 5 2 25
1. Calculate x and y knowing that 17 students got at least 15 and the class average was 15
2. Suppose in what follows that x=5 and y=10

a) Determine the mode and the median.

b) Use the calculator to find the standard deviation 

c) Find the percentage of students whose grades belong to the given set: