If tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting, calculate the focal length of objective

If the tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting, then the focal length of the objective is .......... cm.

If tube length Of astronomical telescope is 105cm and magnifying power is 20 for normal setting, the focal length of the objective is:

The length of the tube of an astronomical telescope is 80 cm and the magnifying power of the instrument is 19 . Calculate the focal lengths of the objective and the eyepiece.

The optical length of an astronomical telescope with magnifying power of ten for normal vision is 44 cm . What is the focal length of the objective ?

The optical length of an astronomical telescope with magnifying power of 10, for normal vision is 44cm. What is focal length of the objective?