Seventh graders collected some gold sand on a class field trip. Class 7A collected 40 oz of gold sand that contains 12% gold.
Class 7B collected 55 oz of gold sand that contains 11% gold.
How much pure gold did 7A collect?

Class 7A collected 4.8 ounces of pure gold.

Step-by-step explanation:

Key skills required are: Percentages, Multiplication

Here we have to do 12% x 40 to find the number of oz of pure gold. We first have to convert 12% into a decimal. Divide it by a 100 (or move the decimal point 2 places to the left) and you will get 0.12.

Do 0.12 x 40 and you will get 4.8

Therefore, there are 4.8 oz of pure gold in Class 7A's gold sand

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.