Rate — O/L Mathematics

How do I practise Rate?

1 question with a worked solution

1. Water flows into an empty rectangular water tank of base area 2.5 m² at a uniform rate of 150 litres per minute. By how many centimetres does the water level rise in 20 minutes?
   1. A) 12 cm
   2. B) 150 cm
   3. C) 120 cm
   4. D) 60 cm
   Check my answer

   Correct answer: C) 120 cm

   Total volume in 20 min = 150 L/min × 20 min = 3000 L = 3 m³ (since 1000 L = 1 m³). Height = Volume / Base Area = 3 m³ / 2.5 m² = 1.2 m = 120 cm.

   Show worked solution

   Step 1: Calculate total volume delivered: V = 150 litres/min × 20 min = 3,000 litres. Step 2: Convert litres to cubic metres: 3,000 litres / 1000 = 3.0 m³. Step 3: Calculate height increase: h = Volume / Area = 3.0 m³ / 2.5 m² = 1.2 m. Step 4: Convert metres to centimetres: 1.2 m × 100 = 120 cm. Answer: 120 cm.
   Modelled on: the O/L Mathematics examination pattern

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Where does Rate fit in the syllabus?

Grade 10 · Term 3