In 02s a coil of die with 50 loops experiences an average

Question

In 0.2s, a coil of die with 50 loops experiences an average induced emf of 9v due to a changing magnetic field perpendicular to the plane of the coil. The radius of the coil is 10 cm and the initial strength of the magnetic field is 1.5T. Assuming that the strength of the field decreased with time,

(a) what is the final strength of the field?

(b) If the field strength had, instead increased what would its final value have been?

(c) Explain a method whereby you could, in principle, tell whether the field was increasing or decreasing magnitude.