# statistics, question 3, grade 10

01/07/2016

3)

The table below shows the scores of 50 students in an exam out of 15.

 Value(xi) 10 11 12 13 14 total Frequency(ni) 5 y 20 x 3 50 Increasing cum. freq.

a) Specify the population and its size; the variable, its values and its kind.

b) Find x and y knowing that 30% of the students got at least 13.

c) Suppose in what follows that x = 12 and y = 10:

i) Calculate  $\overline X \&\sigma$

ii) Specify the mode .

iii) Complete the Increasing cum. freq. table then find the median.

iv) Calculate the number of students whose scores belong to the interval  $\left[{\overline X-\sigma,\overline X+\sigma}\right]$