Solution : (i) The total number of trials =1000.
The frequency of a tyre that needs to be replaced before it covers 4000 km is 20 .
So, P( tyre to be replaced before it covers 4000 km)=100020​=0.02
(ii) The frequency of a tyre that will last more than 9000 km is 325+445=770
So, P( tyre will last more than 9000 km)=1000770​=0.77
(iii) The frequency of a tyre that requires replacement between 4000 km and 14000 km is 210+325=535.
So, P(tyre requiring replacement between 4000 km and 14000 km)=1000535​=0.535