Question

A car cab observed that the average speed of 3 cars was 20 m.p.h., of 5 cars 25 m.p.h. and of 21. 2 cars was 10 m.p.h. over the same route. Find the average speed of a car(Harmonic mean).​

Answer 1

Answer:

$3 \times20 \div 5 - 25 \times 21 + 2 \div 10 \\ = 3 \times 20 \div 20 \times 21 + 2 \div 10 \\ = 3 \times 20 \div 20 \times 23 \div 10 \\ = 60 \div 460 \div 10 \\ = 0.01304347826 - 18900564 \\ = - 1890056399$

answer is complete