Answer:
focal length is 9.65 cm and the power is 10.36 diopter.
Step-by-step explanation:
Now consider the case of concave mirror according to sign convention

And the magnification produced buy it is,

Therefore,

Now focal length is,

Therefore the focal length is 9.65 cm.
Now, the power is,

Therefore,

Therefore the power of the mirror is is 10.36 diopter.