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1/8th part of a pencil is black, half of the remaining is white. If the remaining part is blue and length of this blue part is 31/2cm, then find the length of the pencil ?
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- 6 cm
- 7 cm
- 8 cm
- 9 cm
Correct Option: C
Let the total length of pencil = L cm
Then, black part = L/8
∴ Remaining part = L - L/8 = 7L/ 8
and White part = (7L/8)/2 = 7L/8
∴ Remaining part = L - (L/8 + 7L/16) = 7L/16
∴ length of blue part = 7L/16
According to the question,
7L/16 = 31/2
⇒ 7L/16 = 7/2
∴ L =8
