Grade 9 Data Handling Quiz 1 draws its questions at random from 29 questions across these topics:
A few of the question types, with full solutions, so you know what to expect.
Range. Calculate the range of this set of test scores: 143, 128, 132, 128, 116, 145, 128, 136, 141.
Answer: 29
The range is the largest value minus the smallest value.
Largest = 145 and smallest = 116.
145 − 116 = 29
Range. Which statement about the range is TRUE?
Answer: It measures how spread out the data is
The mean, median and mode are averages — single values that stand for the whole set.
The range does something different: it measures SPREAD.
Stem-and-leaf. The stem-and-leaf diagram shows the Mathematics marks of a Grade 9 class. How many learners wrote the test?
Answer: 20
Each LEAF represents one learner, so count all the leaves.
Row 1 has 5 leaves, row 2 has 7 leaves and row 3 has 8 leaves.
5 + 7 + 8 = 20
Stem-and-leaf. The stem-and-leaf diagram shows a Grade 9 class's Mathematics marks. What is the modal mark?
Answer: 33
The mode is the mark that appears most often.
Reading the marks: 10 and 10, 11 and 11, and 25 and 25 each appear twice.
In the bottom row the leaves 3, 3, 3 all sit on stem 3, giving 33 three times.
Stem-and-leaf. The stem-and-leaf diagram shows a Grade 9 class's Mathematics marks. Determine the median mark.
Answer: 27
There are 20 marks, so the median position is (20 + 1) ÷ 2 = 10,5.
That means we average the 10th and 11th marks.
Counting up: the 10th mark is 26 and the 11th mark is 28.
(26 + 28) ÷ 2 = 27