Question

A tyre manufacturing company kept a record of the distance covered before a tyre needed to be replaced. The table show the result of $1000$ cases :

Distance in $Km$	Frequency
Less than $4000$	$20$
$4000$ to $9000$	$210$
$9000$ to $14000$	$325$
More than $14000$	$445$

If you buy a tyre of this company what is the probability that it will need to be replaced after it has covered somewhere between $4000km$ and $14000km$?

• A. $0.65$
• B. $0.625$
• C. $0.125$
• D. None of these
  

Answer 1

Answer: (D)

None of these

Probability that it will need to be replaced before it has covered $4000$ km $=\frac{20}{1000}=0.02$
Probability that it will last more than $9000km=\frac{325+445}{1000}=\frac{770}{1000}=0.77$

Probability that it will need to be replaced after it has covered somewhere between $4000$ km and $14000$ km = $\frac{210+325}{1000}=\frac{535}{1000}=0.535$