الرياضيات (بالإنجليزية) الصف السادس الابتدائي، الأسبوع 23: Choosing a method for a percent problem

Percent of a quantity, discounts and budgets

الأسبوع 23 · النسبة المئوية من كمية والخصومات ومسائل النسبة · 3 دروس

Choosing a method for a percent problem

Discover Mathematics P6: Term 2, Unit 10, Lessons 10–11

GoalChoose a method for a multi-step percent problem and check the answer.

New words

budget · a plan for how much money to spend on each thingmethod · a way of solving a problemmulti-step · a problem that needs more than one calculation

Explanation

Percent problems come in several shapes, so choose a method that fits. For a friendly percent (10%, 20%, 25%, 50%, 75%) use a fraction. For other percents use 10% and 5% steps, or 1%. For “what percent?” write a fraction and change it into hundredths. For “find the whole”, use a tape. In a budget the percents of all the parts add up to 100%, so you can find the last part by subtracting. When two shops give different discounts, work out BOTH final prices in LE and compare the prices, not the percents. Finally, check: is the answer a sensible size?

★Remember

Match the method to the question: part, percent or whole? Friendly percent: fraction. Other: 10%, 5%, 1% steps. Last: is the answer sensible?

Worked examples

Part	Percent	Amount (LE)
Food	40%	240
Transport	25%	150
The rest	35%	210

A budget of 600 LE: food takes 40% and transport takes 25%. Food = 40% of 600 = 240 LE. Transport = 25% of 600 = 150 LE. The rest is 600 − 240 − 150 = 210 LE, which is 100% − 40% − 25% = 35% of the budget. Check: 35% of 600 = 210.

Two shops sell the same bag. Shop A: 300 LE with 20% off, so 300 − 60 = 240 LE. Shop B: 260 LE with 10% off, so 260 − 26 = 234 LE. Shop B is cheaper by 6 LE, even though its percent is smaller.

Yara got 36 out of 40 in a test. The fraction is 36/40 = 9/10 = 90/100, so her mark is 90%.

Class activity

My budget. You are given 400 LE to spend. Make a budget with four parts and a percent for each (they must add up to 100%). Write how many LE each part gets.

Practice

A family budget is 800 LE. Food takes 30% and transport 25%. How many LE are left?

Shop A sells a watch for 500 LE with 10% off. Shop B sells it for 480 LE with 5% off. Which is cheaper?

Karim read 27 of the 60 pages of his book. What percent has he read?

Marwan has 400 LE. He spends 35% on a gift. How much does he spend and how much is left?

A fridge costs 8,000 LE. The price falls by 10%, then falls by 10% of the NEW price. Is it now 6,400 LE? Work it out.