Question: total of 40 students in class, boys number is double of the girls number. How many boys & girls in the class?
Working as follow:
a = boy b = girl
2a + b = 40
2a + 2a = 40
4a =40
a =10
b=2a
b = 2x 10
b = 20
So a=10, b= 20. Total only 30, not 40 . Why?
Thanks
So girls make up 1/3 of group, while boys make up 2/3.
1/3 *40 = 13. 3 rounded to 13
40 - 13 = 27
Do you have typos?
To solve this problem, you correctly set up the equation:
2a + b = 40
However, when you substituted the value of "a" back into the equation, you made a mistake. Instead of writing "2a + 2a = 40," it should be "2a + b = 40."
So, let's correct your mistake:
2a + b = 40
2(10) + b = 40
20 + b = 40
Now, to solve for "b," we need to isolate it:
b = 40 - 20
b = 20
So, the number of boys is 10, and the number of girls is 20, which adds up to the desired total of 40 students in the class.