Statistics - Mean and Standard Deviation for Grouped Data

Statistics - Mean and Standard Deviation for Grouped Data

Secondary 4
8 marks

The frequency table below summarizes the volume of apple juice dispensed from vending machine \(A\) for \(50\) trials.

Volume from \(A\) (\(x\) ml)Frequency
\(246 < x \le 248\)\(4\)
\(248 < x \le 250\)\(7\)
\(250 < x \le 252\)\(28\)
\(252 < x \le 254\)\(6\)
\(254 < x \le 256\)\(5\)
  1. For vending machine \(A\), calculate
    1. the mean,[2]
    2. the standard deviation.[2]
  2. Another vending machine \(B\) is used to dispense apple juice. The mean and standard deviation of the volumes of apple juice dispensed by vending machine \(B\) is \(251.36\) ml and \(2.22\) ml respectively. The nominal volume of each cup of apple juice dispensed from these vending machines is \(250\) ml. If you run a vending machine business, which machine would you buy? Explain your choice.[2]
    1. What is the range of volume dispensed by machine \(A\)?[1]
    2. Why is the standard deviation preferred over the range as a measure of the spread of data?[1]

Video Solution:

Video Solution

Video solution locked

A free account saves your progress; this video needs a course plan.

Solution:

Solution locked

680+ questions here come with free worked solutions. A free account saves your questions and progress; this one needs a course plan.

Answer:(a)(i) Estimated \(251.04\) ml. (a)(ii) Estimated \(1.98\) ml. (b) Machine A: closer mean and smaller spread. (c)(i) Exact range unknown; \(6<R<10\) ml. (c)(ii) Standard deviation uses all observations, whereas range uses only the extremes.

Need help? Join our E-Maths tuition for O-Level success.

Learn more