The amount of a radioactive material has been reduced to 24 percent of the original value. If the half-life is 6230 years, the age of the sample is estimated to be :a) 6160 years b) 19100 years c) 8890 years d) 12800 years e) 25700 years

d) 12800 years.

Step-by-step explanation:

The equation for the decay of radioactive material has the following form:

Where is the time constant.

There is a relation between half-life and time constant:

The estimated age of the sample is isolated from the decay equation:

The correct answer is D.  

10.416 m/s

step-by-step explantion:

distance=100m

time= 9.6s

average speed=100/9.6

=10.416 m/s