E-Math: How to Use the Mean and Standard Deviation Formula (Plus: Calculator Shortcuts)

One of the first topics that many Secondary 4 E-Math students learnt is a statistics chapter known as Mean and Standard Deviation (SD for short).

The nice thing about this chapter is that the 2 most important formula are both available in the E-Math (subject code: 4016) formula sheet! No memorization required, just understanding of their usage.

In this post, I will illustrate 2 methods to get the answers for mean and SD for ungrouped data (refer to example). The 2 methods are manual and calculator.


Given 15, 6, 18, 9, 2 and 4, find the mean and standard deviation.


Mean and Standard Deviation Manual Working
Mean and Standard Deviation Manual Working

Calculator, Casio fx-85MS:

  1. Mode, 2(SD)
  2. Enter the data in this manner, 15, M+ follows by 6, M+...
  3. To get mean: Press 'Shift', 2, 1,=
  4. To get SD: Press 'Shift', 2, 2,=

Here are some additional information you can obtain using the calculator:

Mean - SD from Calculator
Mean - SD from Calculator

Answers obtained through both methods are the same. By knowing these 2 methods, you can use either to double check.

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Hi, I'm Ai Ling Ong. I enjoy coaching students who have challenges with understanding and scoring in 'O' Level A-Maths and E-Maths. I develop Math strategies, sometimes ridiculous ideas to help students in understanding abstract concepts the fast and memorable way. I write this blog to share with you the stuff I teach in my class, the common mistakes my students made, the 'way' to think, analyze... If you have found this blog post useful, please share it with your friends. I will really appreciate it! :)

One Response to E-Math: How to Use the Mean and Standard Deviation Formula (Plus: Calculator Shortcuts)

  1. thank you for registering me. i love maths and want to improve my knowledge of o level maths.
    kind regards,
    steve okpachu


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