Maths

posted by .

There are 36 pupils in a class. Each girl is given 8 books and each boy is given 3 books. The total number of books the girls receive is 46 more than the total number of books the boys receive. How many girls are there in the class?

The ratio of the number of boys to that of girls in Class A is 2:3. The ratio of the number of girls who wear glasses to the number of girls who do not wear glasses is 1:3. If there are 12 more girls than boys, how many girls wear glasses?

The average height of 3 girls is 150cm. The heights of two of them are 1.6 m and 1.47 m. What is the height of the third girl?

A regular tank 40cm by 20cm by 20cm is filled with water up to 2/5 of its height. Water from a tap flows into the tank at 2.5 liters a minute. How much water is in the tank after 3 minutes? Give your answer in liters. (1Liter= 1000cm3)

  • Maths -

    GB = 8*G
    BB = 3*B
    GB - BB = 46

    Where GB is the number of girl's books, BB is the number of boy's books, G is the number of girls, and B is the number of boys.

    Use algebra to solve this system of equations

    2nd problem

    B/G = 2/3
    G(glasses) + G(noglasses) = G
    G(glasses)/G(noglasses) = 1/3
    G - B = 12

    where B is number of boys, G is number of girls, G(glasses) is number of girls with glasses, G(noglasses) is number of girls without glasses

    Use algebra to solve this system of equations

    3rd question:

    1.6 m = 160 cm; 1.47 m = 147 cm

    (160 + 147 + x) / 3 = 150

    where x is the height of the third girl. Solve for x

    4th question

    The water in the tank before the tap turns on is

    2/5 * 40 * 20 * 20 = 3200 cm3 = 3.2 L

    After three minutes, 2.5 * 3 = 7.5 L

    The total amount of water in the tank is 3.2 L + 7.5 L

  • Maths -

    1. number of girls ---- x
    number of boys --- 36-x

    8x - 3(36-x) = 46
    8x - 108 + 3x = 46
    11x = 154
    x = 14

    There are 14 girls in the class

    2. number of boys = 2x
    number of girls = 3x
    1/4 of the girls wear glasses, or
    (3/4)x girls wear glasses

    "there are 12 more girls than boys" ---> x - (36-x) = 12
    2x = 48
    x = 24

    There are 24 girls , and 1/4 of those wear glasses
    Then 6 girls wear glasses

    check:
    24 girls and 12 boys, ratio is 12:24 = 2:3 , checks
    1/4 of the 24 girls wear glasses ---> 6 girls wear glasses
    ratio of glassed girl to non-glassed girls = 6 : 18 = 1:3 , checks
    All is good!


    3. (x+1.6+1.47)/3 = 1.50
    x+1.6+1.47 = 4.5
    x = 1.43

    Third girl is 1.43 m or 143 cm tall

    4. rate of flow = 2.5 L/min
    after 3 minutes new amount of water = 3(2.5) = 7.5 L
    plus the (2/5)(40)(20)(20) or 6400 mc^3 or 6.4 L already in tank
    gives us 13.91 L

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. math,(fraction)

    there were 25pupils in a class. they had 135 books altogether. two-fifth of the pupils were girls.they had the same number of books each. the remaining pupils were boys.each boy had one-third as many as each girl.how many books did …
  2. math

    MEghan had 36 books in her locker. Some were library books, text books and the rest were telephone books. THe number of library books and phone books combined equals twice the number of text books. The number of text books and telephone …
  3. math

    The ratio of mystery books to the number of science fiction books is 4:3. The number of sci-fi books to the number of biographies is 4:5. If there are 48 sci-fi books what is the total number of books
  4. math

    the library has a total collection of 2630 books. the number of non-fiction books is 240 fewer than the number of fiction books but 190 more than the number of picture books. how many books of each type are there in the library?
  5. math

    the library has a total collection of 2630 books. the number of non-fiction books is 240 fewer than the number of fiction books but 190 more than the number of picture books. how many books of each type are there in the library?
  6. math

    the library has a total collection of 2630 books. the number of non-fiction books is 240 fewer than the number of fiction books but 190 more than the number of picture books. how many books of each type are there in the library?
  7. math

    there are 40 pupils in a class. each girl is given 5 books and each boy is given 4 books.the girls have 65 more books than the boys. how many more girls than boys are there in the class?
  8. math

    Percy wrote this equation to represent the total number of books he carried in two bags. 12 = 7 + b ⁢       Which situation could be described by this equation?
  9. help azap math

    Percy wrote this equation to represent the total number of books he carried in two bags. 12 = 7 + b ⁢       Which situation could be described by this equation?
  10. Math-Ratios

    In a college library, there are 4 times as many nonfiction books as fiction books. A.Find the ratio of the number of nonfiction books to the number of fiction books. B.How many times the number of nonfiction books is the number of …

More Similar Questions