Subject: General Aptitude · Chapter: Area · Exam: 2007 · Marks: · Difficulty:
If the cost of gardening is ` 85 per square metre then what will be the cost of gardening 1.4 metre wide strip inside around a circular field having an area of 1386 square metres?
Answer
Answer (as printed):
Explanation
Let the radius of the circular field be R metres. 1386 × 7 Then, pR2 = 1386 ⇒ R2 = = 441 ⇒ R = 441 = 21 m. 22 Radius of field excluding strip, r = (21 – 1.4) m = 19.6 m. Area of strip = p (R2 – r2) = p [(21)2 – (19.6)2] 22 2 22 2 = (441 – 384.16) m = × 56.84 m = 178.64 m2. 7 7 \ Cost of gardening = ` (178.64 × 85) = ` 15184.40.
Explanation as extracted from the printed page; notation may be imperfect.