The ratio of the number of boys and girls in a college is 7 : 8. If the percentage increase in the number of boys and girls be 20% and 10% respectively, what will be the new ratio?

21 : 22

Step-by-step explanation:

Boys : Girls = 7 : 8

Let the number of boy = 7x

the number of girls = 8x

Number of boys after 20% increase = 120% of 7x

                                                           = 1.2 * 7x

                                                            = 8.4 x

Number of girls after 10% increase = 110% of 8x

                                                           = 1.1 * 8x

                                                            = 8.8x                    

After increase in number of boys & girls ,

= 8.4x : 8.8x

= 84 : 88    { reduce to simplest form by giving by 4th table}

= 21 :  22

there are lots of ways.   pick's theorem tells us if the vertices are lattice points the area a is

a = b/2 + i - 1

where b is the number of boundary lattice points and i is the number of interior lattice points.

in the figure i count b=16, i=50 so

a = 8 + 50 - 1 = 57

let's try the shoelace formula.   the area is half the sum of the cross products of the sides.  

a(-2,6)   -2(2)-6(-5) = 26

b(-5,2)   -5(-3) - 2(-2) = 19

c(-2,-3) -2(-3) - (-3)(4) = 18

d(4,-3)   4(3) - (-3)(5) = 27

e(5,3)   5(3) - 3(1) = 12

f(1,3)     1(6) - 3(-2) = 12

a(-2,6)

each of the cross products is twice the area of the triangle with the associated side and one vertex the origin. so the area of abo=26/2=13.

area = (1/2) (26 + 19 +   18 + 27 + 12 + 12) = 57

that checks!

853.3

step-by-step explanation: