Answer:
30% students
Step-by-step explanation:
Let x be the number of total students of a school.
63% are girls then total number of girls = (0.63)x
37% are boys then total number of boys = ( 0.37)x
Now 23% of girls wear contacts then total number of girls
= (0.63x) × 0.23
= (0.1449x)
And 42% of boys wear contacts then total number of boys wearing contacts
= (0.37x) ( 0.42)
= (0.1554)x
Total students wears contacts = ( 0.1449x) + (0.1554x)
= (0.3003x)
Percentage of students wear contacts = × 100
= × 100
= 30%
All 30% students wear contacts.