Answer:
Step-by-step explanation:
1) Total = 30 students
Girls : Boys = 2 : 1
Total part = 2 + 1 = 3
Fraction of girls = 2/3
[tex]Number \ of \ girls = \dfrac{2}{3}*30 = 2*10 = 20\\\\\\Number \ of \ boys = 30 - 20 = 10[/tex]
Answer: 20 girls and 10 boys
2) Total pens = 24
Red :Blue : Black = 3 : 4 : 1
Total parts = 3 + 4 + 1 = 8
[tex]Number \ of \ red \ pens = \dfrac{3}{8}*24=3*3 = 9\\\\\\Number \ of \ blue \ pens = \dfrac{4}{8}*24=4*3=12\\\\\\Number \ of \ black \ pens = \dfrac{1}{8}*24=1*3=3[/tex]
Answer: 9 red pens
12 blue pens
3 black pens
3) Total people = 180
Adults : boys : girls = 3 : 2 : 7
Total parts = 3 + 2 + 7 = 12
[tex]Number \ of \ adults = \dfrac{3}{12}*180=3*15=45\\\\\\Number \ of \ boys = \dfrac{2}{12}*180=2*15=30\\\\\\Number \ of \ girls = \dfrac{7}{12}*180=7*15=105\\\\[/tex]
Answer: 45 adults ; 30 boys and 105 girls
4)Total vehicles = 12000
Cars : trucks : motorcycles = 13 : 8 : 3
[tex]Number \ of \ cars = \dfrac{13}{24}*12000=13 *500 = 6500\\[/tex]
6500 cars drove through on that day
[tex]b) Number \ of \ trucks = \dfrac{8}{24}*1200 = 8*500 = 4000[/tex]
4000 trucks
