Advanced Mathematics Primary 5 Decimals

The total mass of 1 000 identical metal washers is 4.75 kg. Amir places exactly 100 of these washers into a bag. What is the mass of the washers in the bag?

A 0.0475 kg
B 0.475 kg
C 4.75 kg
D 47.5 kg
Show Worked Solution

Worked Solution

Step 1: Find the mass of 1 washer. Mass of 1 washer = 4.75 ÷ 1 000 = 0.00475 kg (Decimal point moves 3 places to the left.) Step 2: Find the mass of 100 washers. Mass of 100 washers = 0.00475 × 100 = 0.475 kg (Decimal point moves 2 places to the right.) Alternative: 100 washers = 100/1 000 = 1/10 of all washers. 4.75 ÷ 10 = 0.475 kg ✓

Correct answer: 0.475 kg

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