3 times 6= 18. The average speed is 19 mph.
hope this helps!
To solve this problem it is necessary to apply the concepts related to intensity as a function of power and area.
Intensity is defined to be the power per unit area carried by a wave. Power is the rate at which energy is transferred by the wave. In equation form, intensity I is
The area of a sphere is given by
So replacing we have to
Since the question tells us to find the proportion when
So considering the two intensities we have to
The ratio between the two intensities would be
The power does not change therefore it remains constant, which allows summarizing the expression to
Re-arrange to find 
Therefore the intensity at five times this distance from the source is 
It would take about 2 thirds of a second or .66666666 repeating of a second. please give brainliest?
The concave mirror is a spherical-shaped mirror that has an inner curved surface. Hence, option (4) is correct.
What is a concave mirror?
The concave mirrors are spherical-shaped mirrors that are painted on the outward surface. It is also known as the converging mirror, having the recessed inner reflecting surface.
- The concave mirrors are generally used for the purpose to focus the light. For that, they might have a reflecting surface, curved inwards, and the reflection of light is limited to the single focal point.
- The reflecting surface of the concave mirror has its vertex or midpoint lying farther away from the objects than the edges.
Thus, we can conclude that the surface of the concave mirror is curved inward. Hence, option (4) is correct.
Learn more about the concave mirror here:
brainly.com/question/13300307
