Question: [Maximum mark: 4]
The number of hours spent exercising each week by a group of students is shown in the following table.
| Exercising time (in hours) | Number of students |
| 2 | 5 |
| 3 | 1 |
| 4 | 4 |
| 5 | 3 |
| 6 | x |
The median is 4.5 hours.
(a) Find the value of x .
(b) Find the standard deviation.
▶️Answer/Explanation
Ans:
(a) EITHER
recognising that half the total frequency is 10 (may be seen in an ordered list or indicated on the frequency table)
OR
5 + 1 + 4 = 3 + x
OR
\(\sum f = 20\)
THEN
x = 7
(b) METHOD 1
1.58429…
1.58
METHOD 2
EITHER
