A stairway 10 ft. high is such that each step accounts for half a foot upward and one foot forward. What distance will an ant travel if it starts from ground level to reach the top of the stairway?
(a)30 ft.
(b)33 ft.
(c)10 ft.
(d)29 ft.
Answer
Answer (as printed): D
Explanation
Number of steps $=\left(10 \div \frac{1}{2}\right)=20$. To reach the top, the ant covers the height of 20 steps and the width of 19 steps because the moment it ascends the height of 20th step, it reaches the top. ∴ Distance travelled by the ant $$=\left[\left(\frac{1}{2} \times 20\right)+(1 \times 19)\right] \mathrm{ft}=(10+19) \mathrm{ft}=29 \mathrm{ft} .$$
Explanation as extracted from the printed page; notation may be imperfect.