Question

A tyre manufacturing company kept a record of the distance covered before a tyre needed to be replaced. The table shows the results of 1000 cases.

(Distance (in km) - Frequency)

Less than 4000 - 20

4000 to 9000 - 210

9001 to 14000 - 325

More than 14000 - 445

If you buy a tyre of this company, what is the probability that(i) it will need to be replaced before it has covered 4000 km ? (ii) it will be replaced after 9000 km ?(iii) it will need to be replaced after it has covered distance somewhere between 4000 km and 14000 km ?

Answer 1

Answer:

(1) 20/1000=0.02

(2)770/1000=0.77

(3)535/1000=0.535

It is by formula

Number of trial/total number of trial

Answer 2

(i) 20 tyres need to be replaced before 4000 km out of 1000 tyres.

probability that the tyre needs to be replaced before covering 4000 km = 20/1000 = 0.02 or 2%

(ii) tyres replaced after 9000 km = 325+445 = 770 tyres out of 1000

probability = 770/1000 = 0.77 or 77%

(iii) tyres replaced between 4000 and 14000 km = 325+210+20 = 555 tyres out of 1000

probability = 555/1000 = 0.555 or 55.5%

I have used:

$probability = \frac{number of desired outcome}{total number of outcomes}$