Gap and difference questions in PSLE math often require students to close the gap and find the difference between two sets of data. This method involves identifying the missing values and calculating the discrepancy to arrive at the correct answer. Let’s explore how to approach such problems using the “Gap and Difference” technique.
Example:
Question: 5 apples and 3 oranges cost $2.70. 2 apples and 4 oranges cost $2.20. How much does a dozen apples cost?
Solution:
To solve this problem, we first need to close the gap between the two sets of data. We can do this by finding the lowest common multiple and multiplying both sets of values accordingly.
Step 1: Close the Gap
To close the gap, we calculate the total cost for each set of items:
| Apples | Oranges | Total |
|---|---|---|
| 5 | 3 | $2.70 |
| 2 | 4 | $2.20 |
By doubling the quantities in the second set, we can close the gap:
| Apples | Oranges | Total |
|---|---|---|
| 10 | 6 | $5.40 |
| 10 | 20 | $11.00 |
Step 2: Compare the Difference
Next, we compare the difference in total cost between the two sets:
$11.00 – $5.40 = $5.60
This difference represents the cost of 14 oranges.
Calculating the Cost of Apples:
1 orange costs $0.40.
4 oranges cost $1.60.
Therefore, the cost of 2 apples is $2.20 – $1.60 = $0.80.
To find the cost of a dozen apples, we multiply the cost of 2 apples by 6:
12 apples = $0.80 x 6 = $4.80
Answer: A dozen apples cost $4.80.
By applying the “Gap and Difference” method, students can effectively solve PSLE math problem sums and arrive at the correct answers with confidence.
This article provides valuable insights and strategies for mastering this essential problem-solving technique in PSLE math.
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