Q.

A 1.5 m tall man walks at a uniform speed of 60 m/min away from a lamp post of height 6 m. Find the rate at which his shadow increases

A. \(\frac{15m}{min}\)

B. \(\frac{24m}{min}\)

C. \(\frac{30m}{min}\)

D. \(\frac{20m}{min}\)

E. \(\frac{25m}{min}\)

D. \(\frac{20 m}{min}\)

\(\Rightarrow\) \(\frac{6}{1.5}\) = \(\frac{a+b}{b}\) = \(\frac{4}{1}\)

= a + b = 4b

= a = 3b

\(\Rightarrow\) Time to travel dist “a” = \(\frac{a}{60}\)min

\(\frac{a}{60}\)min  \(\rightarrow\) b

1 min \(\rightarrow\)  ?

= \(\frac{1×b}{a/60}\)

= 20 m/ min