Rekha has 15 square colour papers of sizes 10 cm, 11 cm, 12 cm, …, 2

1.	Rekha has 15 square colour papers of sizes 10 cm, 11 cm, 12 cm, …, 24 cm. How much area can be decorated with these colour papers?
Answer» Area of 15 square colour papers = 10² + 11² + 12² + … + 24² = (1² + 2² + 3² + … + 24²) – (1² + 2² + 9²) = (24 x 25 x 49)/6 - (9 x 10 x 19)/6 = 4 x 25 x 49 – 3 x 5 x 19 = 4900 – 285 = 4615 Area can be decorated is 4615 cm²

Rekha has 15 square colour papers of sizes 10 cm, 11 cm, 12 cm, …, 24 cm. How much area can be decorated with these colour papers?

Answer»

Area of 15 square colour papers

= 10² + 11² + 12² + … + 24²

= (1² + 2² + 3² + … + 24²) – (1² + 2² + 9²)

= (24 x 25 x 49)/6 - (9 x 10 x 19)/6

= 4 x 25 x 49 – 3 x 5 x 19

= 4900 – 285

= 4615

Area can be decorated is 4615 cm²