Answer :
Final answer:
The mean mark for the girls in the class is calculated to be 28.2, rounded to three significant figures, by subtracting total marks of the boys from total marks of all students and dividing the result by number of girls.
Explanation:
To calculate the mean mark for the girls, we first need to calculate the total mark for the entire class, then subtract the total mark obtained by all the boys. We can calculate the total mark for all students by multiplying the mean mark by the total number of students.
We can calculate the total boys' marks by multiplying the mean mark for the boys by the number of boys. Then, subtract total boys' marks from total students' marks to get total girls' marks.
Finally, divide total girls' marks by the number of girls to get their mean mark.
Step 1: Calculate total marks of all students = mean mark of students * total number of students = 26.8 * 30 = 804.
Step 2: Calculate total marks of boys = mean mark of boys * number of boys = 25 * 13 = 325.
Step 3: Calculate total girls' marks = total marks of all students - total marks of boys = 804 - 325 = 479.
Step 4: Calculate mean mark for the girls = total girls' marks / number of girls = 479 / (30 - 13) = 28.176, which can be rounded to 28.2 to three significant figures.
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