Timmy drove 2/5 of a journey at an average speed of 20 mph. He drove the remaining 60 miles at another speed. If the average speed was 25 mph, what’s the amount of time for the whole journey?

An electromagnetic wave with frequency 65.0 hz travels in aninsulating magnetic material that has dielectric constant 3.64 andrelative permeability 5.18 at this frequency. the electric fieldhas amplitude 7.20 \times 10^{ - 3} {\rm v}/{\rm m}. a. what is the speed of propagation of the wave? b.what is the wavelength of the wave? c.what is the amplitude of the magnetic field? d.what is the intensity of the wave?