2006-10-03 23:00:51 · 15 answers · asked by shldnfrederick 1 in Science & Mathematics ➔ Mathematics
the number of boys= (5/12)*840=350
no of girls=840 - 350= 490
thats the answer
2006-10-03 23:16:06 · answer #1 · answered by shubham.ghosh 1 · 0⤊ 0⤋
840/ 5+7 = 70 therefore number of boys = 5 x 70 = 350 and number of girls = 490 ...... 490 + 350 = 840
2006-10-03 23:31:55 · answer #2 · answered by moonfunpie 1 · 0⤊ 0⤋
840/ (5+7) = 840/12 = 70. therefore for every (5x70) boys there are (7x70) girls.
Therefore there are 1. 5 x 70 boys = 350 boys
and 2. 7 x 70 girls = 490 girls.
Check... 350 boys + 490 girls = 840 students. Thus these answers are correct!
2006-10-03 23:07:47 · answer #3 · answered by Anonymous · 0⤊ 0⤋
5/12*840 = 350 boys
7/12*840 or 840-350 = 490
2006-10-03 23:10:44 · answer #4 · answered by Anonymous · 0⤊ 0⤋
number of boys is 350. number of girls is 490.
add 5 and 7 to get 12. divide total students by 12 (that = 70), then times 70 by 5 for total boys (=350) and times 70 by 7 for total girls (=490). double check answer by adding 350 and 490 = 840 (total students)
2006-10-03 23:06:24 · answer #5 · answered by mhm 3 · 0⤊ 0⤋
350 boys, 490 girls.
840 divided by 12 = 70
70 x 5 = 350
70 x 7 = 490
2006-10-03 23:03:05 · answer #6 · answered by Anonymous · 2⤊ 0⤋
Let x represent the number of boys, and y the number of girls.
Now we know that x+y=840 (all boys and girls are 840), and x:y=5:7.
We have two equations and two unknowns:
x+y=840
x:y=5:7
Solving the equations for x and y (see Note) yields:
x=350 (number of the boys)
y=490 (number of girls)
Note:
x=840-y (eq.1)
7x=5y (eq. 2)
7(840-y)=5y (substituting x from eq.1 in eq.2)
5880=12y
y=490,
x=350
2006-10-03 23:57:52 · answer #7 · answered by Anonymous · 1⤊ 0⤋
5+7=12 parts
5 out of 12 parts boys...5/12*840=350 boys
Similarly for girls it is 7/12*840=490 girls
Better you do your own home work...at least try
2006-10-03 23:05:35 · answer #8 · answered by robin 3 · 1⤊ 0⤋
Total students=840
RATIO OF bOYS TO GIRLS =7/5
nO. OF BOYS = 7/12 * 840 =490
NO.OF GIRLS =840-490=350
2006-10-04 01:57:56 · answer #9 · answered by Anonymous · 0⤊ 0⤋
5:7 ---> 5 + 7 = 12
840 x (5/12) = number of boys
840 x (7/12) = number of girls
boys = 350
girls = 490
2006-10-03 23:34:54 · answer #10 · answered by wolfwood 2 · 0⤊ 0⤋