Paper 4 · statistics - mean and standard deviation
A stem-and-leaf diagram of pocket money (in dollars) received by a group of girls is given below, with key : Stem 0: 50 50 50 75 Stem 1: 00 00 00 50 75 Stem 2: 00 00 00 50 50 Stem 3: 00 25 30 75 Stem 4: 50 Stem 5: 50 What is the mean pocket money received, to the nearest cent?
A$2.14
B$2.25
C$2.04
D$1.95
Explanation: Reading off all 20 values in cents (50,50,50,75,100,100,100,150,175,200,200,200,250,250,300,325,330,375,450,550), the total is 4280 cents. Dividing by the correct count of 20 values gives a mean of 214 cents = $2.14; using an incorrect number of data values as the divisor gives the wrong mean.
Derived from ZIMSEC Maths Paper 1, November 2008, Q1 (Statistics)
