Mathematics
Drawing pencils cost 80 paise each and coloured pencils cost ₹1.10 each. If altogether two dozen pencils cost ₹21.60, how many coloured pencils are there ?
Answer
Let no. of drawing pencils be x and no. of coloured pencils be y.
Total pencils = 24.
⇒ x + y = 24
⇒ x = 24 - y …….(i)
Total cost = ₹21.60
⇒ 0.80x + 1.10y = 21.60
⇒ 0.80(24 - y) + 1.10y = 21.60
⇒ 19.2 - 0.80y + 1.10y = 21.60
⇒ 19.2 + 0.30y = 21.60
⇒ 0.30y = 2.40
⇒ y = 8.
Substituting value of y in (i) we get,
x = 24 - y = 24 - 8 = 16.
Hence, no. of coloured pencils = 8.
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