(a) Show this information in a stem and leaf diagram.(3)
One of these students is going to be chosen at random.
The pass mark in the French test is 71
Omar writes,
The probability that this student failed the French test is \(\dfrac{1}{4}\)
Omar is wrong.
(b) Explain why. (2)
Mark scheme (a)
Answer
Mark
Mark scheme
Stem and leaf diagram
B2
for correct ordered stem and leaf
(B1
for fully correct unordered or ordered with one error or omission)
B1
(indep) for key (units not required but must be correct if stated) eg 6 | 4 = 64 (marks)
Correct diagram
6
4799
7
0015667
8
0011247
9
14
Mark scheme (b)
Answer
Mark
Mark scheme
Explanation
C1
for identifying “6” students failed (ft their diagram) OR for \(20 \div 4\ (= 5)\)
C1
for comparing \(\dfrac{1}{4}\) with \(\dfrac{6}{20}\) or \(\dfrac{3}{10}\) (ft their diagram) OR for comparing “6” with 5
Additional guidance
Explanation does not need to state that Omar is wrong, but just needs to provide two comparable values (that are not the same) unless ft values show that Omar is not wrong in which case a statement is needed.
