IB Mathematics SL 4.3 Measures of central tendency AA SL Paper 1- Exam Style Questions- New Syllabus
Claire rolls a six-sided die 16 times. The scores obtained are shown in the following frequency table.
Score | Frequency |
---|---|
1 | \( p \) |
2 | \( q \) |
3 | 4 |
4 | 2 |
5 | 0 |
6 | 3 |
It is given that the mean score is 3.
Part (a):
Find the value of \( p \) and the value of \( q \). [5]
Part (b):
Each of Claire’s scores is multiplied by 10 in order to determine the final score for a game she is playing. Write down the mean final score. [1]
▶️ Answer/Explanation
Part (a)
Find the value of \( p \) and \( q \).
Total rolls = 16, so:
\[ p + q + 4 + 2 + 0 + 3 = 16 \]
\[ p + q + 9 = 16 \]
\[ p + q = 7 \quad (1) \]
Mean score = 3:
\[ \frac{(1 \cdot p) + (2 \cdot q) + (3 \cdot 4) + (4 \cdot 2) + (5 \cdot 0) + (6 \cdot 3)}{16} = 3 \]
\[ p + 2q + 12 + 8 + 0 + 18 = 48 \]
\[ p + 2q + 38 = 48 \]
\[ p + 2q = 10 \quad (2) \]
Subtract (1) from (2):
\[ (p + 2q) – (p + q) = 10 – 7 \]
\[ q = 3 \]
Substitute into (1):
\[ p + 3 = 7 \]
\[ p = 4 \]
Verify: Frequencies sum = \( 4 + 3 + 4 + 2 + 0 + 3 = 16 \).
Mean: \[ \frac{4 + 6 + 12 + 8 + 0 + 18}{16} = \frac{48}{16} = 3 \]
Answer: \( p = 4 \), \( q = 3 \)
Part (b)
Write down the mean final score.
Each score is multiplied by 10. Mean final score = original mean × 10:
\[ 3 \cdot 10 = 30 \]
Answer: 30