In a school, $\dfrac{1}{25}$ of the students were absent on a certain day. If 720 students were present on that day, what is the total number of students in the school?

Given,

Total students present on a certain day = 720

Part of students absent on a certain day = $\dfrac{1}{25}$

Part of students present on a certain day = $1 - \dfrac{1}{25}$

$= \dfrac{25 - 1}{25} \\[1em] = \dfrac{24}{25}.$

Number of students present on a certain day = Part of students present on a certain day × Total number of students

$\Rightarrow 720 = \dfrac{24}{25} \times \text{ Total number of students} \\[1em] \Rightarrow \text{ Total number of students} = 720 \times \dfrac{25}{24} \\[1em] \Rightarrow \text{ Total number of students} = 30 \times 25 = 750.$

Hence, total number of students in the school = 750.