If pendulum A makes 15 oscillations in 5 seconds, and pendulum B makes 12 oscillations in 3 seconds. Which pendulum has a higher pitch  A or B?

Frequency refers to the number of sound waves that pass a given point in a second, while pitch is the perceived highness or lowness of a sound. High-pitched sounds have high-frequency waves.

Here, we will calculate the frequencies of pendulum A and pendulum B.
The frequency of pendulum A (f_A) is given by,
     $\mathrm{Frequency}\left({\mathrm{f}}_{\mathrm{A}}\right)=\frac{\mathrm{no}. \mathrm{of} \mathrm{oscillations}}{\mathrm{time} \mathrm{taken}}$
$\Rightarrow \mathrm{Frequency} \left({\mathrm{f}}_{\mathrm{A}}\right)=\frac{15}{5}$ 

$\Rightarrow \mathrm{Frequency} \left({\mathrm{f}}_{\mathrm{A}}\right)=3\mathrm{Hz}$     …………………….. (i)
Now, the frequency of pendulum B (f_B) is given by
$\Rightarrow \mathrm{Frequency} \left({\mathrm{f}}_{\mathrm{B}}\right)=\frac{12}{3}$
$\Rightarrow \mathrm{Frequency} \left({\mathrm{f}}_{\mathrm{B}}\right)=4 \mathrm{Hz}$     …………….......………… (ii)
From equations (i) and (ii), we can say (f_B) > (f_A)
Therefore, pendulum B has a higher frequency as compared to pendulum A.

Hence, pendulum B has a high pitch.