Math, asked by kuldeepautophase, 5 months ago

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Answers

Answered by mahadev112021
1

Answer:

One third of a certain journey is covered at the rate of 25 km/hour, one-fourth at the rate of 30 km/hour and the rest at 50 km/hour. The average speed for the whole journey is

35 km/hour

33

1

km/hr

3

30 km/hour

37

1

km/hr

12

Correct Option: B

Let the total distance be x km.

Total time =

x

x

5x

3

+

4

+

12

25 30 50

=

x

+

x

+

x

75 120 120

=

x

+

x

75 60

=

4x + 5x

=

3x

hours

300 100

∴ Average speed =

Total distance

Time taken

=

x

3x

100

=

100

= 33

1

kmph

3 3

Second Method :

Here, x = 3, u = 25, y = 4, v = 30

z =

12

, w = 50

5

Average Speed =

1

1

+

1

+

1

xu yv zw

=

1

1

+

1

+

1

3 × 25 4 × 30 (12/5) × 50

=

1

1

+

1

+

1

75 120 120

=

1

1

+

1

75 60

=

1

4 + 5

300

=

300

=

100

9 3

= 33

1

km/hr.

3

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