Practice Test

1) D. E. of lines, passing through the origin, is

2) D. E. of all circles, having centres at the origin, is

3) The standard unit circle satisfies the D. E.

4) Population of city increases at a rate proportional to the population. Within a period of 30 years the population grew from 20 lakhs to 40 lakhs. After a further period of 15 years, the population of the city (in lakhs) will be

5) A population grows at the rate of 5% per year. Then the population will be doubled in

6) An ice ball melts at a rate proportional to the amount of ice present at that instant. If half the quantity of ice melts in 20 minutes, then after an hour, the amount of ice left will be

7) Rate of decay of radium varies as the amount present. If 60 mg are present now and the half-life of radium is 1690 years, then the amount of radium present 100 years from now is

8) A person's assets start reducing in such a way that the rate of reduction of assets is proportional to the square-root of the assets existing at that time. If the assets at the beginning are Rs. 10 lakhs and they dwindle down to Rs. 10,000 after 2 years, then the person will be bankrupt in n years from the start, where : n =