Example 6
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.
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?
Total number of trials = 1000.
Frequency of tyre that needs to be replaced before it covers 4000 km = 20.
So, P (tyre to be replaced before it covers 4000 km) = 20/1000 = 0.02
Example 6
If you buy a tyre of this company, what is the probability that :
(ii) it will last more than 9000 km?
Total number of trials = 1000.
Frequency of tyre that it will last more than 9000 km
= Frequency of tyre that will last 9001 to 14000 km
+ Frequency of tyre that will last more than 14000 km
= 325 + 445 = 770
So, P(tyre will last more than 9000 km) = 770/1000 = 0.77
Example 6
If you buy a tyre of this company, what is the probability that :
(iii) it will need to be replaced after it has covered somewhere between 4000 km and 14000 km?
Total number of trials = 1000.
Frequency of tyre that requires replacement b/w 4000 & 14000 km
= Frequency of tyre that will last b/w 4000 to 9000 km
+ Frequency of tyre that will last b/w 4001 to 14000 km
= 210 + 325 = 535
P(tyre requiring replacement between 4000 km and 14000 km)
= 535/1000 = 0.535

Made by

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.