Step by step solution :
standard deviation is given by :

where,
is standard deviation
is mean of given data
n is number of observations
From the above data, 
Now, if
, then 
If
, then 
if
, then 
If
, then 
If
, then 
so, 



No, Joe's value does not agree with the accepted value of 25.9 seconds. This shows a lots of errors.
Answer: A and B
Explanation:
Electromagnetic radiations are examples of electromagnetic waves with increasing frequency and decreasing wavelength in the following order radiowaves - infrared waves - visible lights - ultraviolet rays- x-rays - gamma rays.
They did not require material medium for their propagation.
The statement above shows that EM radiations possesses different wavelengths and frequency.
Answer:
277.78 hours
Explanation:
The formula for calculating the amount of charge is expressed as;
Q = It
I is the current
t is the time
Given
I =0.05A
Q = 50,000C
Required
Time t
Recall that: Q = It
t = Q/I
t = 50,000/0.05
t = 1,000,000secs
Convert to hours
1,000,000secs = 1,000,000/3600
1,000,000secs = 277.78 hours
Hence it will take 277.78 hours for the charge to flow through the diode
To measure the strength of an earthquake, you can use either a Richter scale or Mercalli scale. Richter scale uses the amplitued of the wave and the distance from the source. Mercalli scale uses observations of people and is not considered to be scientific as Richter scale.