Answer:

Step-by-step explanation:
Total possibilities when we a roll a die at a time are 6
given we should have four for first time and then three
let us assume we rolled the dice we may get 1,2,3,4,5,6(any of these) the probability to get 4 is
PROBABILITY=
Favourable chances=1
Total chances=6
Probability=
the prabability to get 4 in first roll is
.
let us assume we rolled the dice for second time again we may get 1,2,3,4,5,6(any of these) the probability to get 3 is
Favourable chances=1
total chances=6
probability=
the probability to get 3 in second roll irrespective of first one is 
the probability to get 4 in first time and then 3 is
The probability to occur both events at a time is multiplication of individual probabilities
So,
probablility to get 4 in first roll=
probability to get 3 in second roll=
probability to occur both at a same time is =

=
Answer:
I do not agree, because x=4 is an extraneous
Step-by-step explanation:
First, to solve the equation, you subtract 3 from both sides, then square both sides, subtract one from both sides, and finally divide by 2 on both sides. This indeed gets us x=4, but we also need to check if it's an extraneous solution. To do that we simply plug in x=4 into the original equation. sqrt( 2(4) + 1 ) + 3 = 0. When we do this, we end up with ±3 + 3 = 0. I do not agree, because we don't know if the sqrt(9) is -3 or 3.
Answer:
Mean=50.
standard deviation=50.
Step-by-step explanation:
Let the perfect score be 100.
The mean(average) of a data is given by: 
Here the number of data points are 100. out of which 50 attains a value 100,and 50 attains value 0.
so, sum of data points=50×100+50×0=5000.

Mean=50.
"Now the standard deviation of data points are calculated by firstly subtracting mean from every entry and then square the number and take it as new entry and calculate the mean of the new data entry and lastly taking the square root of this new mean".
Here if 50 is subtracted from each entry the new entry will have 50 entries as '50' and 50 entries as '-50'.
next on squaring we will have all the 100 entries as '2500'.
now the mean of these entries is: 
=2500
taking it's squareroot we have 
Hence, standard deviation=50.
There are 1000000 megabytes in a terabyte :)
If your divide 7,500 by 2 1/2 hours, you get 3,000, the number of grass seeds laid per hour