An organ pipe closed at one end has fundamental frequency of 1500 Hz. The maximum number of overtones generated by this pipe, which a normal person can hear is?

Dear student, 

The frequencies in a closed organ pipe are given as- $\frac{\nu }{4L},\frac{3\nu }{4L},\frac{5\nu }{4L},\frac{7\nu }{4L}...$
According to the question, $\frac{\nu }{4L}=1500 \mathrm{Hz}$
Then for first overtone, frequency = 3$\times$1500 Hz = 4500 Hz
​For second overtone, frequency = 5$\times$1500 Hz = 7500 Hz
For third overtone, frequency = 7$\times$1500 Hz = 10500 Hz
Similarly, the frequency of sixth overtone will be = 13​​$\times$1500 Hz = 19500 Hz
Since the hearing range of a normal person is upto 20000 Hz, we can infer that a upto 6 overtones can be heard by a normal person.

Hope this clears your doubts.
Regards