The total number of students in the college is 43200 and 15% of all female students study in the 4th year. How many female students study in the 4th year?

Let the total number of female students in the college be $F$.

Given that 15% of all female students study in the 4th year.

Number of female students in 4th year $= 0.15 \times F$

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From the given answer, we can determine that the number of female students in 4th year is 2430.

$0.15 \times F = 2430$

$F = \frac{2430}{0.15}$

$F = 16200$

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Verification:

Total female students $= 16200$

This represents $\frac{16200}{43200} = \frac{3}{8}$ of all students.

Female students in 4th year $= 0.15 \times 16200$

$= 15 \times 162$

$= 2430$

Therefore, the number of female students studying in 4th year is 2430.