Calculation of Space Mean Speed And Time Mean Speed

Problem: Collect time required by 4 vehicles for traveling 1km were 1.6, 1.2, 1.5, & 1.7 minutes respectively. Find space mean speed and time mean speed?
Exam Name: PGCL 2017
 
Solution:
Speed of four vehicles are,
             V₁ = (1/1.6)*60 =37.5 km/hr
             V₂ = (1/1.2)*60 = 50 km/hr
             V₃ = 1/1.5*60   = 40 km/hr
             V₄ = 1/1.7*60   =35.29 km/hr
$$Vs=\frac{n}{\sum _{ }^{ }\frac{1}{Vi}\:}=\:\frac{4}{\frac{1}{37.5}+\frac{1}{50}\:+\frac{1}{40}+\frac{1}{35.29}\:\:}$$

   V_s = 40 km/h


Time mean speed is the average of spot speed
          

$$Vt=\frac{\sum Vi\:}{n}$$

= (37.5+50+40+35.29)/4
= 40.7km/h

Answer:  Space mean speed 40 km/h and time mean speed 40.7 km/h

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