A tank of 100 litres is filled with kerosene. Ram replaces 10% of kerosene with water and repeats this procedure 4 times. What is the amount of kerosene left in the tank? Pick one.
A) 65.60 litres	B) 65.71 litres	C) 25.61 litres	D) 65.61 litres	E) 65.31 litres
Explanation:   As Ram replaces 10% of kerosene with water, the amount of kerosene left is 90%.   As the replacement is done four times,   After 1st replacement, kerosene left is :   0.9*100= 
<gadget id="calculator">  0.9*100</gadget>
<output>90</output>
90 litres   After 2nd replacement, kerosene left is :   0.9*90= 
<gadget id="calculator">  0.9*90</gadget>
<output>81</output>
81 litres   After 3rd replacement, kerosene left is :   0.9*81= 
<gadget id="calculator">  0.9*81</gadget>
<output>72.9</output>
72.9 litres   After 4th replacement, kerosene left is :   0.9*72.9= 
<gadget id="calculator">  0.9*72.9</gadget>
<output>65.61</output>
65.61 litres   ANSWER: 65.61 litres
<result>D</result>
A tank of 100 litres is filled with kerosene. Ram replaces 10% of kerosene with water and repeats this procedure 4 times. What is the amount of kerosene left in the tank?