In a class, \( 4 / 5 \) of the students are boys and rest are girls. If \( 2 / 5 \) of the boys and \( 1 / 4 \) of girls are absent, what part of the total number of students is present?
Step-by-step Solution:
If 4/5 of the students are boys, then the remaining part represents the girls.
Girls = 1 − 4/5 = 1/5 of the students.
If 2/5 of the boys are absent, then the proportion of boys present is 1 − 2/5 = 3/5.
Part of total students who are boys and present = (Proportion of boys) × (Proportion of boys present)
= 4/5 × 3/5 = 12/25.
If 1/4 of the girls are absent, then the proportion of girls present is 1 − 1/4 = 3/4.
Part of total students who are girls and present = (Proportion of girls) × (Proportion of girls present)
= 1/5 × 3/4 = 3/20.
Total present = 12/25 + 3/20 Convert to common denominator (100): 12/25 = 48/100, 3/20 = 15/100 Total present = 48/100 + 15/100 = 63/100.
The part of the total number of students present is (B) 63/100.