krit.club logo

Scientific Enquiry - Recording data in tables and bar charts

Grade 3IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

A Data Table is used to organize information clearly. It consists of columns (vertical) and rows (horizontal).

•

Headings in a table must include the unit of measurement. For example, if measuring length, the heading should be Length (cm)\text{Length (cm)}. Units should not be repeated in every cell of the table.

•

A Tally Chart is often used during the data collection process. Each mark ∣| represents one item, and a group of five is shown as ∣∣∣∣\cancel{||||}.

•

A Bar Chart is a visual way to display data. The height or length of the bars represents the value of each category.

•

The X-axis (horizontal) usually shows the categories or labels, while the Y-axis (vertical) shows the numerical scale.

•

The Scale on the Y-axis must use equal intervals, such as counting by 2s2s, 5s5s, or 10s10s. For example, a scale might go 0,5,10,15,200, 5, 10, 15, 20.

•

Every bar chart must have a Title and clearly labeled axes so the reader knows what the data represents.

📐Formulae

Total Count=∑individual tallies\text{Total Count} = \sum \text{individual tallies}

Scale Interval=Value between two grid lines\text{Scale Interval} = \text{Value between two grid lines}

Range=Maximum Value−Minimum Value\text{Range} = \text{Maximum Value} - \text{Minimum Value}

💡Examples

Problem 1:

A student measures the mass of three stones as 12 g12\text{ g}, 15 g15\text{ g}, and 9 g9\text{ g}. How should the table header for these measurements be written?

Solution:

Mass (g)\text{Mass (g)}

Explanation:

In scientific recording, the unit (grams, represented by gg) is placed in the column heading in brackets so that the numbers 12,15,12, 15, and 99 can be written clearly without repeating the letter 'g' each time.

Problem 2:

If a bar chart has a Y-axis scale where each grid line represents 22 units, what is the value of a bar that reaches halfway between the 1010 and 1212 marks?

Solution:

1111

Explanation:

Since the interval is 22, the midpoint between 1010 and 1212 is calculated as 10+122=11\frac{10 + 12}{2} = 11.

Problem 3:

Look at these tally marks for 'Blue Cars' seen in a car park: ∣∣∣∣∣∣∣∣∣∣\cancel{||||} \cancel{||||} ||. What is the total frequency?

Solution:

1212

Explanation:

Each group of ∣∣∣∣\cancel{||||} represents 55. Therefore, the total is calculated as 5+5+2=125 + 5 + 2 = 12.