# How to Calculate Mean & Standard Deviation by Calculator (Sharp EL-W531 series)

/These are the instructions to calculate mean & standard deviation by the Sharp EL-W531 series calculators.

I have tested this on the Sharp EL-W531S and SHARP EL-W531XM calculators.

For those taking GCE O Levels Mathematics, take note you have to still have to show proper workings to obtain full marks.

Use the calculator to *check* your answer!

Take note of the rarely used buttons required.

- The
**,**(comma) button - The
**CHANGE**button

They are above the right bracket **)** button.

##
**Clearing Memory**

Always clear the memory before entering any values.

**Steps**

- Press
**2nd F**followed by**ALPHA** - You will get the following screen:

- Press
**1**to select*1: MEMORY* - You will get the following confirmation screen:

- Press
**0**to clear memory

##
**Step 1: Select Statistics Mode**

**Steps**

- Press
**MODE** - You will get the following selection screen:

- Press
**1**to select*1: STAT* - You will get the following selection screen:

- Press
**0**to select*0: SD* - You should get the following screen, which indicates that statistics mode is selected.

##
**Step 2: Enter The Data**

The following data will be used as an example. Feel free to follow along.

Mid-value |
Frequency |

5.5 | 5 |

15.5 | 10 |

25.5 | 5 |

35.5 | 18 |

45.5 | 2 |

**Step 2(a)** - Enter the first row: 5.5, 5

- (Clear the memory if you haven't already done so)
- Press
**5.5** - Press
**, (comma)** - Press
**5** - Press
**CHANGE** - You will get the following screen:

If you do not get *DATA SET= 1*, you have to clear the memory and start again.

**Step 2(b)** - Enter the second row: 15.5, 10

- Press
**15.5** - Press
**, (comma)** - Press
**10** - Press
**CHANGE** - You will get the following screen:

**Step 2(c)** - Enter the 3 remaining sets

- Use the same method as described in steps 2(a) and 2(b).
- If all goes well, you should get the following 3 screens:

**Step 2(d)** - Check the entries

Mid-value (X) |
Frequency (F) |

5.5 | 5 |

15.5 | 10 |

25.5 | 5 |

35.5 | 18 |

45.5 | 2 |

- Use the ▲ ▼ directional keys to check the entries. They should correspond to the table above.
- If you do not get the any of the following 5 screens or have extra DATA SETs, clear the memory and start from step 2(a) again.

**Step 2(e)**

- Press
**ON/C**

##
**Step 3: Obtain the mean and standard deviation**

To obtain the mean:

- Press
**ALPHA** - Press
**4** - Press
**=** - You will obtain the mean:

To obtain the standard deviation:

- Press
**ALPHA** - Press
**6** - Press
**=** - You will obtain the standard deviation:

Once done, press **MODE** followed by **0** to go back to normal mode.

##
**Practice Question and Closing Thoughts**

The following table shows the number of goals scored by the first twenty Manchester United players in the 2012/2013 title winning season.

Number of goals |
Frequency |

0 | 5 |

1 | 4 |

2 | 3 |

3 | 2 |

4 | 2 |

5 | 1 |

16 | 1 |

18 | 1 |

30 | 1 |

Calculate the mean and standard deviation.

*Ans: Mean = 4.65, Standard Deviation: 7.55 (3 s.f.)*

For those taking O Levels, use the calculator to *check your answer*. You still have to apply the formulas and show workings in order to score full marks!