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 appropriately
- 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.
Sample question 1 - Foundation
Question
The number of a species of moths decreased from 100,000 to 20,000 in 10 years. Calculate the percentage decrease in the number of moths in 10 years. [2 marks]
This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.
Remember to show all of your working
\(\%~decrease =\) \(\frac{(Starting~number-final~number)}{Starting~number}\times100\)
= \(\frac{(100,000 - 20,000)}{100,000}\times 100\) (1)
= 80% (1)
Sample question 2 - Foundation
Question
Being able to roll your tongue is an inherited characteristic. The students in five year 7 classes were asked whether they could roll their tongue. The results are shown in the table below. Calculate the mean percentage of year 7 students that can roll their tongue. [2 marks]
| Class | 7P1 | 7T2 | 7Y1 | 7G3 | 7W1 |
| Tongue rollers (%) | 25 | 28 | 67 | 45 | 15 |
| Class |
|---|
| 7P1 |
| 7T2 |
| 7Y1 |
| 7G3 |
| 7W1 |
| Tongue rollers (%) |
|---|
| 25 |
| 28 |
| 67 |
| 45 |
| 15 |
This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.
\(Mean =\) \(\frac{(25 + 28 + 67 + 45 + 15)}{5}\)
(1 mark for showing working)
= 36% (1)
You always need to show your working. Your answer should be given to two significant figures because all of the percentage values in the table are given to two significant figures.
Sample question 3 - Higher
Question
The diagram shows the actual size of the dish after incubation.
This table is used to analyse the results of the experiment.
| Area clear of bacteria including the area of the disc in mm squared | Level of resistance |
| less than 133 | resistant |
| 133 to 416 | intermediate resistance |
| more than 416 | not resistant |
| Area clear of bacteria including the area of the disc in mm squared | less than 133 |
|---|---|
| Level of resistance | resistant |
| Area clear of bacteria including the area of the disc in mm squared | 133 to 416 |
|---|---|
| Level of resistance | intermediate resistance |
| Area clear of bacteria including the area of the disc in mm squared | more than 416 |
|---|---|
| Level of resistance | not resistant |
Use the results of the experiment and the table to judge the level of resistance in this strain of bacteria. (The area of a circle = \(\pi\) r2 and \(\pi\) = 3.14.)
Answer = ..........mm2 [3 marks]
OCR Gateway, GCE Biology, Paper J247 - Higher, 2016.
It is important that you have all of your equipment. This question requires you to have a calculator. You should pay attention to all parts of the question - the examiners have given you an equation to help you!
Radius = 2.4 cm/2 = 1.2 cm
1.2 cm = 12 mm
Area = \(\pi\) x radius2 = 3.14 x 122
Area = 452.16 mm2
1 mark for calculating radius in mm, 1 mark for correctly calculating area
not resistant (1)
