There are 10 girls and 20 boys in a class. The class has a test. The mean mark for all the class is 70.
The mean mark for all the boys is 62 Work out the mean mark for the girls.

74 marks

Step-by-step explanation:

As there are 10 girls and 20 boys, there are a total of 30 students in the class.

If the mean mark for all 30 students is 70, this means that there was a combined total score of 70 x 30 = 2100.

If the mean mark for all 10 boys was 62, this means that there was a combined total score for boys of 62 x 10 = 620.

2100 - 620 = 1480 marks in total for the girls

As there are 20 girls in the class, 1480/20 = 74

This means that the mean for the girls in the class is 74 marks.

x=-2

infinite number of lines, so there is an infinite number of equations.

step-by-step explanation:

there are an infinite number of line that passes through the point (-2,5)

x=-2   is one line that passes through the point

y = 5 is another line that passes through the point

(these two lines are perpendicular to each other).

since the number of   numbers are infinite and the slope is the ratio of two numbers,(change in y over change in x) we can have an infinite number of slopes.     our only condition is that it passes through the point (-2,5)

answer: group b.

step-by-step explanation: