Science calculations
Maths questions often start with the command words 'calculate' or 'determine'. They will then have a blank space for you to show your working. It is important that you show your working; don’t just write the answer down. You might earn marks for your working even if you get the answer incorrect.
In some maths questions you will be required to give the units. This may earn you an additional mark. Don't forget to check whether you need to do this.
Maths questions might include graphs and tables as well as calculations. Don't forget to take a ruler and calculator.
If drawing graphs, make sure you:
- put the independent variable on the x-axis and the dependant variable on the y-axis
- construct regular scales for the axes
- label the axes appropriate
- plot each point accurately
- decide whether the origin should be used as a data point
- draw a straight or curved line of best fit
If you are asked to calculate an answer and it has lots of decimal places, don't forget to use the same number of significant figures as the data in the question. For example, if two significant figures are used in the question, then usually your answer would also be to two significant figures. Don't forget to check your rounding.
Edexcel questions courtesy of Pearson Education Ltd.
Sample question 1 - Foundation
Question
Research shows that overweight people may develop type 2 diabetes.
Body Mass Index (BMI) can be used to identify people who are overweight. BMI can be calculated using the equation:
\(\text{BMI =}\frac{\text{mass in kilograms}}{\text{height in metres \times height in metres}}\)
Calculate the BMI for a person who has a mass of 77 kilograms and a height of 1.6 metres [2 marks]
\(\frac{77}{1.6 \times 1.6}\) (1 mark)
= \(30\) (1 mark)
Accept two marks for correct answer.
Accept the 30.07 to 30.08, or 30.1.
Sample question 2 - Higher
Question
A diabetic athlete is advised to estimate the number of grams of carbohydrate in his meals in order to calculate the number of units of insulin he will need to inject to lower his blood glucose concentration.
Each unit of insulin he injects reduces his blood glucose concentration by 1.5 mmol/dm3.
He needs to inject 1 unit for every 10 grams of carbohydrate he consumes. The table shows the estimated carbohydrates in the breakfast eaten by the athlete.
| Food | Carbohydrate |
| Orange juice | 25 |
| 2 slices brown toast | 68 |
| 350 grams baked beans | 38 |
| Tea with sugar | 25 |
| Food | Orange juice |
|---|---|
| Carbohydrate | 25 |
| Food | 2 slices brown toast |
|---|---|
| Carbohydrate | 68 |
| Food | 350 grams baked beans |
|---|---|
| Carbohydrate | 38 |
| Food | Tea with sugar |
|---|---|
| Carbohydrate | 25 |
Calculate how many units of insulin the athlete would need to inject to control the rise in blood glucose levels.
Give your answer to two significant figures. [2 marks]
156 Ă· 10 (1 mark)
= 16 units (1 mark)
Answer to two significant figures