Mathematics

A student measured the length of a room and obtained the measurement of 3.99m. If…

A student measured the length of a room and obtained the measurement of 3.99m. If the percentage error of is measurement was 5% and his own measurement was smaller than the length , what is the length of the room?

  • A.
    3.78m
  • B.
    3.80m
  • C.
    4.18m
  • D.
    4.20m
  • E.
    4.788m
Correct Answer: Option D
Explanation

Let the actual length of the room = y m

(therefore frac{y – 3.99}{y} times 100% = 5%)

(100(y – 3.99) = 5y implies 100y – 399 = 5y)

(100y – 5y = 399 implies y = frac{399}{95})

y = 4.2 m