What is the greatest possible length (in cm) of scale to measure exactly the following lengths: 1m 20 cm, 3m, 90cm ?

Correct option is A

Given:

Given lengths are 1m 20cm, 30 m and 90 cm

Formula Used:

1m = 100cm

Solution:

1 m 20 cm = 120 cm

3 m =300 cm

HCF of 120 cm, 300 cm and 90 cm

120 = $$2^3 \times 3 \times 5$$​​

300 = $$2^2 \times 3 \times 5^2$$​ 

90 = $$2 \times 3^2 \times 5$$​ 

HCF = $$2 \times 3 \times 5$$​ = 30cm