A person travels from P to Q at the speed of 20 km/h , from Q to R at 25 km/h, and from R to Z at 50 km/h . If PQ = QR = RZ , then find the person's average speed ( in km/h ) .
Answer & explanation
Correct answer: option 1
Let , PQ = QR = RZ = x
Total Distance = 3x
Distance = Speed × Time
Total Time = \(\frac{x}{20}\) + \(\frac{x}{25}\) + \(\frac{x}{50}\)
= \(\frac{11x}{100}\)
Average Speed = \(\frac{Total\; Distance }{Total\;Time}\)
= \(\frac{3x\;×\;100 }{11x}\)
= \(\frac{3\; × \;100}{11}\) = \(\frac{300}{11}\)