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Solve the Following Question.(4 Marks)

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33 questions · self-marked practice — reveal the answer and mark yourself.

Question 14 Marks
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 moment. If the assets at the beginning are ₹ 10 lakhs and they dwindle down to ₹ 10,000 after 2 years, show that theperson will be bankrupt in $2 \frac{2}{9}$ years from the start.
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Question 24 Marks
The volume of a spherical balloon being inflated changes at a constant rate. If initially its radius is 3 units and after 3 seconds it is 6 units. Find the radius of the balloon after t
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Question 34 Marks
The normal lines to a given curve at each point (x, y) on the curve pass through (2, 0). The curve passes through (2, 3). Find the equation of the curve.
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Question 44 Marks
Find the particular solution of the following differential equations:

$\left( x +2 y ^2\right) \frac{d y}{d x}= y$, when $x =2, y =1$

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Question 64 Marks
Obtain the differential equation by eliminating the arbitrary constants from the following equations:

$y =\sqrt{a \cos (\log x)+b \sin (\log x)}$

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Question 74 Marks
In each of the following examples verify that the given function is a solution of the differential equation.

$y=3 \cos (\log x)+4 \sin (\log x) ; x^2 \frac{d^2 y}{d x^2}+x \frac{d y}{d x}+y=0$

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Question 84 Marks
In each of the following examples verify that the given function is a solution of the differential equation.

$y = e ^{ ax } \sin bx ; \frac{d^2 y}{d x^2}-2 a \frac{d y}{d x}+\left(a^2+b^2\right) y=0$

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Question 94 Marks
Water at $100^{\circ} \mathrm{c}$ cools in 10 minutes to $88^{\circ} \mathrm{c}$ in a room temperature of $25^{\circ} \mathrm{c}$. Find the temperature of water after 20 minutes.
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Question 104 Marks
Bismath has half life of 5 days. A sample originally has a mass of $800 \mathrm{mg}$. Find the mass remaining after 30 days.
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Question 134 Marks
Find the particular solution with given initial conditions : $\frac{y-1}{y+1}+\frac{x-1}{x+1} \cdot \frac{d y}{d x}=0$, when $x=y=2$
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Question 144 Marks
Find the particular solution with given initial conditions : $\frac{d y}{d x}=e^{2 y} \cos x$ when $x=\frac{\pi}{6}, y=0$
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Question 154 Marks
Form the differential equation of family of circles above the $\mathrm{X}$-axis and touching the $\mathrm{X}$-axis at the origin.
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Question 164 Marks
The rate of growth of the population of a city at any time t is proportional to the size of the population. For a certain city, it is found that the constant of proportionality is 0.04. Find the population of the city after 25 years, if the initial population is 10,000. [Take e = 2.7182]
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Question 174 Marks
Assume that a spherical raindrop evaporates at a rate proportional to its surface area. If its radius originally is 3 mm and 1 hour later has been reduced to 2 mm, find an expression for the radius of the raindrop at any time t.
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Question 184 Marks
A right circular cone has a height of $9 cm$ and a radius of the base of $5 cm$. It is inverted

and water is poured into it. If at any instant the water level rises at the rate of $\left(\frac{\pi}{A}\right) cm / sec$,

where A is the area of the water surface at that instant, show that the vessel will be full in 75 seconds.

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Question 194 Marks
Find the population of a city at any time t, given that the rate of increase of population is proportional to the population at that instant and that in a period of 40 years, the population increased from 30,000 to 40,000.
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Question 204 Marks
The rate of growth of bacteria is proportional to the number present. If initially, there were 1000 bacteria and the number doubles in 1 hour, find the number of bacteria after 2½ hours. [Take √2 = 1.414]
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Question 214 Marks
If the population of a country doubles in 60 years; in how many years will it be triple (treble) under the assumption that the rate of increase is proportional to the number of inhabitants? [Given log 2 = 0.6912, log 3 = 1.0986]
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Question 224 Marks
In a certain culture of bacteria, the rate of increase is proportional to the number present. If it is found that the number doubles in 4 hours, find the number of times the bacteria are increased in 12 hours.
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Question 234 Marks
The curve passes through the point (0, 2). The sum of the coordinates of any point on the curve exceeds the slope of the tangent to the curve at any point by 5. Find the equation of the curve.
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Question 244 Marks
Solve the following differential equations:

$\left(1-x^2\right) \frac{d y}{d x}+2 x y=x\left(1-x^2\right)^{\frac{1}{2}}$

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Question 304 Marks
Solve the following differential equations:

$\left(1+e^{\frac{x}{y}}\right) d x+e^{\frac{x}{y}}\left(1-\frac{X}{y}\right) d y=0$

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Question 324 Marks
Solve the following differential equations:

$\left(1+2 e^{\frac{x}{y}}\right)+2 e^{\frac{x}{y}}\left(1-\frac{x}{y}\right) \frac{d y}{d x}=0$

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