Answers:
a) 222.22 m/s
b) 800.00 km/h
Explanation:
The speed of a wave is given by the following equation:
Where:
is the speed
is the frequency, which has an inverse relation with the period 
is the wavelength
Solving with the given units:
This is the speed of the wave in km/h
Transforming this speed to m/s:

This is the speed of the wave in m/s
The jigsaw can be used to make both straight and curved cuts in a wide variety of materials, including wood, particleboard, plywood, plastic, metal, even ceramic tile. There is also way more than those, but those are just the basics or common things. Hope this helps!
It depends on the circuit. Sometimes it becomes a bit weaker, sometimes it stays the same.