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3 w from the g in the b?
3 wishes from the genie in the bottle
3 b in the g s?
3 Bears in the Goldilocks Story
In a class of 21 students the ratio of boys to girls is 4 to 3 Three extra boys and one extra girls join the class What is the new ratio of boys to girls?
B/G = 4/3 so 3B = 4G B+G = 21 Multiply by 3: 3B+3G = 63 But 3B = 4G so 4G+3G = 63 ie 7G = 63 so that G = 9 So B+G=21 means B = 12 3 more boys so B' = 12+3 = 15 1 more girl so G' = 9+1 = 10 So new ratio = B'/G' = 15/10 = 3/2 or 3 to 2
One half of the students in alex's science class are girls one third of the girls in the class have blonde hair if 10 girls do not have blonde hair how many students are in alex's science class?
Let's say that s is the total number of students, b is the number of boys, g is the total number of girls, n is the number of non-blonde girls, and e is the number if blonde girls. We know that s = b + g, b = g, g = n + e, e = g/3, and n = 10. Substituting for b in the first equation gives us s = g + g = 2g Then we substitute for n and e in the third equation and solve for g: g = g/3 + 10 g - g/3 = 10 g - (1/3)g = 10 (2/3)g = 10 g = 10 x (3/2) = 15 Finally, solve for s: s = 2g = 2 x 15 = 30
When 5 new girls joined the class the percent of girls increased from 40 percent to 50 percent what is the number of boys in the class?
Let us use the letter G for the number of girl in the class and B for the number of boy. The total number of students is B+G. We are told the original percent of girls went from 40 to 50 %. So when there was 40% girls, we had G/(B+G) =.4 Now we add 5 new girls and the percent of girls is .5 So (G+5)/(B+G+5)=.5 Let's cross multiply the first equation and we have .4G+.4B= G or .4B=.6G B=(3/2)G The second equation becomes (G+5)=(1/2)G+(1/2)B+(5/2) This is the same as 2G+10=G+B+5 Or G=B-5 Now plug in B=(3/2)G G=(3/2)G-5 or -1/2 G=-5 or G=10 This means B was (3/2)x10=15. So at first we had 10/25 girls or 40% then when we added 5 girls we have 15/30 girls or 50% So in the original class we had 10 girls and 15 boys and then we had 15 girls and 15 boys. This could be done without the equations, since the numbers are pretty easy in this case. But this method works for any numbers.
