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LevelNEB Class 12
StreamManagement
SubjectBusiness Mathematics
Year2077 BS
Exam sessionModel questions
Full marks40
Time allowed90 minutes
Questions12, all with step-by-step solutions
A

Group 'A'

Attempt all questions.

8 questions·2 marks each
1aShort answer2 marks

Find the domain and range in relation R={(4,8),(4,12),(5,10),(6,12),(7,7)}R=\{(4,8),(4,12),(5,10),(6,12),(7,7)\}.

Domain = set of first elements ={4,5,6,7}=\{4,5,6,7\}.

Range = set of second elements ={8,12,10,7}={7,8,10,12}=\{8,12,10,7\}=\{7,8,10,12\}.

relationsdomain-and-range
1bNumeric answer2 marks

Find the first term of a G.P. whose fifth term is 243 and common ratio is 3.

Numeric answer

sequence-and-seriesgeometric-progression
2aShort answer2 marks

Find the slope and intercepts of the line 2x3y+10=02x-3y+10=0.

Rewrite as y=23x+103y=\dfrac{2}{3}x+\dfrac{10}{3}.

Slope m=23m=\dfrac{2}{3}.

yy-intercept: set x=0y=103x=0\Rightarrow y=\dfrac{10}{3}.

xx-intercept: set y=02x+10=0x=5y=0\Rightarrow 2x+10=0\Rightarrow x=-5.

coordinate-geometrystraight-line
2bNumeric answer2 marks

Evaluate: limx3x3x24x\displaystyle\lim_{x\to 3}\dfrac{x-3}{\sqrt{x-2}-\sqrt{4-x}}.

Numeric answer

limits
3aShort answer2 marks

Find dydx\dfrac{dy}{dx} when x=2atx=2at, y=at2y=at^2.

dxdt=2a\dfrac{dx}{dt}=2a, dydt=2at\dfrac{dy}{dt}=2at.

dydx=dy/dtdx/dt=2at2a=t\dfrac{dy}{dx}=\dfrac{dy/dt}{dx/dt}=\dfrac{2at}{2a}=t.

differentiationparametric
3bShort answer2 marks

If the marginal revenue function for output xx is MR=x3+4x2MR=x^3+4x-2, find the total revenue function.

Total revenue R=MRdx=(x3+4x2)dx=x44+2x22x+CR=\displaystyle\int MR\,dx=\int (x^3+4x-2)\,dx=\dfrac{x^4}{4}+2x^2-2x+C.

Since R=0R=0 when x=0x=0, the constant C=0C=0. Hence R=x44+2x22xR=\dfrac{x^4}{4}+2x^2-2x.

business-mathrevenue-functionintegration
4aNumeric answer2 marks

Find the mean deviation from mean of the following observations.

x68101214161820
f114252718942

Numeric answer

statisticsmean-deviation
4bNumeric answer2 marks

If 200 men can make an embankment 3 km long in 25 days, how much overtime per day must 60 men work to complete an embankment 2 km long in 32 days; 12 hours being a day's work?

Numeric answer (hours/day)

work-timevariation
B

Group 'B'

Attempt all questions.

4 questions·4 marks each
5Long answer4 marks

Solve by Cramer's rule: x+y+z=6x+y+z=6, 2x+3yz=52x+3y-z=5, 3x+4y+5z=263x+4y+5z=26.

Coefficient determinant D=111231345=1(15+4)1(10+3)+1(89)=19131=5D=\begin{vmatrix}1&1&1\\2&3&-1\\3&4&5\end{vmatrix}=1(15+4)-1(10+3)+1(8-9)=19-13-1=5.

Dx=6115312645=6(15+4)1(25+26)+1(2078)=1145158=5D_x=\begin{vmatrix}6&1&1\\5&3&-1\\26&4&5\end{vmatrix}=6(15+4)-1(25+26)+1(20-78)=114-51-58=5, so x=1x=1.

Dy=1612513265=1(25+26)6(10+3)+1(5215)=5178+37=10D_y=\begin{vmatrix}1&6&1\\2&5&-1\\3&26&5\end{vmatrix}=1(25+26)-6(10+3)+1(52-15)=51-78+37=10, so y=2y=2.

Dz=1162353426=1(7820)1(5215)+6(89)=58376=15D_z=\begin{vmatrix}1&1&6\\2&3&5\\3&4&26\end{vmatrix}=1(78-20)-1(52-15)+6(8-9)=58-37-6=15, so z=3z=3.

Solution: x=1, y=2, z=3x=1,\ y=2,\ z=3.

matricescramers-rulesystem-of-equations
6Long answer4 marks

Find the derivative from first principles: y=1xy=\dfrac{1}{x}.

dydx=limh0f(x+h)f(x)h=limh01x+h1xh=limh0x(x+h)hx(x+h)=limh0hhx(x+h)=limh01x(x+h)=1x2\dfrac{dy}{dx}=\lim_{h\to0}\dfrac{f(x+h)-f(x)}{h}=\lim_{h\to0}\dfrac{\frac{1}{x+h}-\frac{1}{x}}{h}=\lim_{h\to0}\dfrac{x-(x+h)}{h\,x(x+h)}=\lim_{h\to0}\dfrac{-h}{h\,x(x+h)}=\lim_{h\to0}\dfrac{-1}{x(x+h)}=-\dfrac{1}{x^2}.

differentiationfirst-principles
7Long answer4 marks

Find the extreme values of the function FF defined by F=10x+15yF=10x+15y subject to constraints x+2y20x+2y\le 20, x+y16x+y\le 16, x0x\ge 0, y0y\ge 0.

Corner points of the feasible region: intersection of x+2y=20x+2y=20 and x+y=16x+y=16: subtracting gives y=4y=4, x=12x=12. Vertices: (0,0)(0,0), (16,0)(16,0), (12,4)(12,4), (0,10)(0,10).

Evaluate F=10x+15yF=10x+15y: at (0,0)=0(0,0)=0; at (16,0)=160(16,0)=160; at (12,4)=120+60=180(12,4)=120+60=180; at (0,10)=150(0,10)=150.

Maximum F=180F=180 at (12,4)(12,4); minimum F=0F=0 at (0,0)(0,0).

linear-programming
8Long answer4 marks

Ram, Shyam and Hari invest in a business with capitals Rs. 5000, Rs. 4500 and Rs. 6500 respectively. After six months, Ram doubles his capital and after next three months Shyam trebles his capital. If the profit at the end of the year amounted to Rs. 8300, find the profit obtained by each.

Compute capital × months (in months over the year):

Ram: Rs.5000 for 6 months ++ Rs.10000 (doubled) for 6 months =5000×6+10000×6=30000+60000=90000=5000\times6+10000\times6=30000+60000=90000.

Shyam: Rs.4500 for 9 months ++ Rs.13500 (trebled) for 3 months =4500×9+13500×3=40500+40500=81000=4500\times9+13500\times3=40500+40500=81000.

Hari: Rs.6500 for 12 months =78000=78000.

Ratio =90000:81000:78000=90:81:78=30:27:26=90000:81000:78000=90:81:78=30:27:26. Total parts =83=83.

Profit Rs.8300 ÷ 83 = Rs.100 per part.

Ram =30×100==30\times100= Rs.3000; Shyam =27×100==27\times100= Rs.2700; Hari =26×100==26\times100= Rs.2600.

partnershipprofit-sharing

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The NEB Class 12 Business Mathematics 2077 paper carries 40 full marks and is meant to be completed in 90 minutes, across 12 questions.
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