Question

5. (a) A car takes 2 hours to reach a destination by travelling at the speed of 60 km/h
. How long will it take when the car travels at the speed of 80 km/h?
(b) A factory requires 42 machines to produce a given number of articles in 63 days
. How many would be required to produce the same number of articles in 54 days
?

Answer 1

(a) please refer to the attachment given below.

(b) If the articles are to be produced in lesser number of days, more machines are required.  

Hence, the number of machines and number of articles are in inverse proportion.

Let the number of machines required to make the articles in 54 days be a

Then, 42:a:: inverse ratio of 63:54

=>42:a=54:63

Applying the rule, product of extremes = product of means

42×63=a×54

a=  

54

42×63

​  

 

a=49

Hence, 49 machines are required to make the articles in 54 days.

Answer 2

Answer:

A.) Given:

Speed :- 60 km/h

Time :- 2 hours

To find:

Time taken to cover the same distance at a speed of 80 km/h

Explanation:

Case 1:-

Speed = (Distance/Time)

• Distance = ( speed × time)

= (60×2) km

= 120 km

* the car travels a distance of 120 km.

Case 2 :-

Distance = 120 km.

Speed = 80 km/h

Distance = (speed × time)

• Time = ( Distance/speed )

=} 120/80

=} 3/2

=} 1 hour = 60 minutes so,

1 hrs = (1×60/2) minutes

= 1 hour 30 minutes

Hence, a car needs 1 hour 30 minutes to complete 80 km/h.