Hi "Good Morning" & Good Night every day?

Question

1.tono is 8 years older than tini. the ratio of their ages is 5:3 . How old will Tini be the nex eight years ?
A.12 years
B.15 years
C.18 years
D.20 years

There are 720 students in a school. the ratio of boys and girls id 7:5. To have ratio 1:1 ,how many girls should be added?

Answer 1

tono. . . . . 5

------ . = . ---

.tini . . . . . 3



Cross-multiply : 3(tono) = 5(tini)



so tono = (tini)5/3





But tono is 8 years older than tini, that is tono = tini + 8





Therefore (tini)5/3 = tini + 8



tini(5/3) - tini = 8



(tini)(2/3) = 8



tini = 8(3/2) = 24/2 = 12



So tini is 12 years old, hence will be 20 years old in 8 years time.







Boys . . . . . 7

------- . = . .----

Girls . . . . . 5





Cross-multiply : 5B = 7G



But B + G = 720



therefore G = 720 - B



So 5B = 7(720 - B)



5B = 5040 - 7B



7B + 5B = 5040



B = 5040/12 = 420



So there are 420 boys and 300 girls.



There needs to be 120 more girls to make the ratio 1 : 1

Answer 2

Tono is 8 years older than Tini.

T = t + 8

the ratio of their ages is 5:3

T/t = 5/3 substitute for t

T/(T - 8)= 5/3

3T = 5T - 40

Eight years from now Tini's age will be t + 8 = T (Tono's present age) = 20 (option D)



Ratio of boys and girls is 7:5 with 720 students

Boys = (7/12)* 720 = 7*60 = 420

Girls = (5/12)* 720 = 5*60 = 300

Need to add 120 girls



Regards - Ian

Answer 3

1) Let Tini's age be x



Tono = ( x+8)



( x+8) / x = 5/3



CROSS MULTIPLY



5x = 3x+24



2x = 24



x = 12



ANSWER Tini = 12+8 = 20 years



2) Let there be 7x boys and 5x girls





12x = 720



x = 60



2x = 120 girls ANSWER

Answer 4

720 students means

boys = 7/12 * 720 = 420

girls = 5/12 * 720 = 300



so 120 more girls need to be added in order to make them equal to boys.

Answer 5

D

120

Answer 6

1) The ages of the two are 20yrs and 12yrs. Not sure what you are asking for rest of the question.

2) At present there are 300 girls, knowing this, you should be able to work out how many boys there are and how many girls you need to add, quite easily.