Three pieces of different lengths are cut from cardboard. The length of third piece is 9/5 of the first. The average length of the first and the second is 11.25 cm. The length of the first piece is 5 times the even prime number. If L is the length of the cardboard, which of the following is/are correct? A. L + 4.5 is a multiple of 9 B. L – 1.5 = 40 C. L + 8.5 is a perfect square D. L/5 = 7
Three pieces of different lengths are cut from cardboard. The length of third piece is 9/5 of the first. The average length of the first and the second is 11.25 cm. The length of the first piece is 5 times the even prime number. If L is the length of the cardboard, which of the following is/are correct? A. L + 4.5 is a multiple of 9 B. L – 1.5 = 40 C. L + 8.5 is a perfect square D. L/5 = 7 Correct Answer A and C
Given:
Length of 3rd piece = 9/5 of length of 1st
Average of length of 1st and 2nd = 11.25 cm
Length of 1st piece = 5 × Even prime number
Formula Used:
Average = Sum of values/Number of values
Calculation:
Only even prime number is 2.
Length of 1st piece = 5 × 2
⇒ 10
Length of 3rd piece = 9/5 × 10
⇒ 18 cm
Sum of Length of 1st and 2nd = Average of length of 1st and 2nd × 2
⇒ Length of 1st + Length of 2nd = 11.25 × 2
⇒ 10 + Length of 2nd = 22.5
⇒ Length of 2nd = 12.5 cm
Length of the cardboard = 10 + 12.5 + 18
⇒ 40.5 cm
⇒ L = 40.5 cm
A. L + 4.5 is a multiple of 9
40.5 + 4.5 = 45
⇒ 5 × 9
⇒ A is correct
B. L – 1.5 = 40
40.5 – 1.5 = 39
⇒ B is not correct
C. L + 8.5 is a perfect square
40.5 + 8.5 = 49
⇒ 72
⇒ C is correct
D. L/5 = 7
40.5/5 = 8.1
⇒ D is not correct
∴ A and C are correct