Answer
120 minutes.
(LCM of the three i.e. 8, 15 and 12 minutes)
Answer
10:151
As, the number of boys is 10 (total-girls=161-151) and the ratio is = Number of boys/Number of girls
Answer
Simple Interest is Rs. 2385.27
For Compound Interest,
Amount=P(1+r)^n
And we know that
Interest=Amount-Principle
Here
Interest=Rs. 2850
r=0.12 p.a.
t=4 years
Hence P= Rs. 4969.32
For Simple Interest,
Interest=Prt (=4969.32*.12*4)
Hence
Simple Interest= Rs. 2385.27
Answer
Assuming that the circle intercepts x-axis at A (a,0) and y-axis at B(0,b) and let O be the origin i.e.,(0,0)
You can draw a circle for the same and name the points for better understanding.
The points A and B form a right angle at the circle (OA and OB i.e., the x and y axis form a 90° angle).
Hence, the line AB is the diameter of the circle.
The centre of the circle is the mid point of AB.
To find C (the centre) or mid point of AB:
C(x,y)= (A(a,0) + B(0,b))/2
Or
x=(a+0)/2
y=(0+b)/2
C(x,y)=(a/2,b/2)
The radius,r of the circle is OC, AC or BC.
Hence diameter= 2r=√(a^2+b^2)
Using the equation of circle:
(i.e., X^2+Y^2=r^2)
(X-a/2)^2 + (Y-b/2)^2 = (a^2+b^2)/4
Answer
207.69%
Let total number of students be 100x
Students passed is 75x (i.e. 75% of 100x)
Therefore, number of failed students is 25x (100x-75x)
Number​ of Girls passed = 75x*0.55 (55% of 75x)
Remaining are boys, hence
Number of Boys passed = 75x * .45 (100% -55%)
Similarly
Number of boys failed= 25x * 0.35
Hence number of Girls failed = 25x * 0.65
Percentage of
Passed boys/ failed girls= (75x * 0.45 * 100)/ (25x *0.65)
=207.69%
Answer
120 girls.
Boys to girls ratio = 7:5
Let the number of boys be 7x
Number​ of girls = 5x
Hence total students = 5x+7x =12x
Total students=720
720= 12x
X= 60
Therefore
Boys = 7x = 420 (=7*60)
Girls = 5x = 300 (=5*60)
Hence we need 120 (420-300) more girls so that the ratio could be 1:1
(i.e., number of Girls=number of Boys)
Answer
Rate is 20%
Given,
Principle,P = Rs. 1000
Time,t = 2 years
For Simple Interest,
Rate, r= 11%
S.I.= P*r*t (= 1000 * 0.11 * 2)
Interest = Rs. 220
Therefore
Compound Interest = Rs. 440 (= 220*2 = S.I *2)
Let the rate be r
Compound Interest= Amount - Principle
Where, Amount = P * (1+r)^t
Hence
440 = 1000 * (1+r)^2 - 1000
1440 = 1000 * (1+r)^2
1.44 = (1+r)^2
1+r = 1.20
Rate,r = 0.20 =20% 
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