How many combinations are possible if 3 one rupee coin, 4 fifty paise coin and 2 twenty five paise coin
are available. It is compulsory to select any one of the coin
Out of 3 one rupee coin, total possible combinations are
0 one rupee coin, 1 one rupee coin,
2 one rupee coin, 3 one rupee coin,
Out of 4 fifty paise coin, total possible combinations are
0 fifty paise coin, 1 fifty paise coin, 2 fifty paise coin, 3 fifty paise coin, 4 fifty paise coin,
Similarly out of 2 twenty five paise coin, total possible combinations are
0 twenty five paise coin, 1 twenty five paise coin, 2 twenty five paise coin,
Therefore total number of methods = 4*5*3 – 1= 60-1 = 59
(1 case is deducted because in a case no coin is selected)
6^3 = three power of six = 15 (total letters used in written expression)
Similarly 4^2 = two power of four = 14
8^4 = four power of eight = 16
And 9^5 = five power of nine = 15
For obtaining 31 zeros at last of the number, 31 powers of 5 is necessary. Product 1*2*3*4*5……………upto 125
contain 5, 10 ,15………. 125. These 25 numbers are multiple of 5, besides it 25, 50, 75, 100, 125 contain
a second 5 and 125 contains a third 5 hence total number of 5 = 25+5+1 = 31
A carom board is of size 2.5 m × 2.5 m. Striker is placed on a side at a position 0.5 m from the left corner.
For overcoming the condition of foul it is necessary to touch the queen placed on right side at a position 0.5 m
from the side where striker is placed. If player wants to make a two collision rebound then he should make
an impact on the first side at a distance of
OPtion
1) 0.8 m from corner
2) 1 m from corner
3) 0.5 m from corner
4) 0.75 m from corner
5) 0.6 m from corner
6) 1.25 m from corner
7) 1.4 m from corner
8) 1.3 m from corner
9) 1.5 m from corner
10) 0.25 m from corner
Solution
Let striker makes first impact at a distance x from the corner and second at a distance y from other corner.
First draw a plot for this condition. Then according to plot
x/0.5 = (2.5-x)/y => xy = 0.5(2.5-x) ..... Equation 1
and y/(2.5-x) = (2.5-y)/2 => 2y =(2.5-x) (2.5-y) .....Equation 2
On solving these equations we get x = 0.75 m