Answer
Rectangle or Square
Why
Only square and rectangle has the property of having a 2 90 degrees angle or right angle.
Hi,
Here we are going to be working on isolating the variable y, and seeing what its value equates to.
To do this, we must try and get the variable y on one side of the equation by itself.
Let's look at step one -
<em>4y - 1 = 7
</em>
We want to get rid of the 1 since we need to isolate x. We do this by doing the inverse of its operation. Since 1 is negative, if we add positive 1 to it - we will get 0, thereby being closer to isolating y.
However, when we do something on one side of the equation we must do it on the other. This means we will add 1 on both sides.
<em>4y - 1 + 1 = 7 + 1
</em>
<em>4y = 8
</em>
<em />Remember how I mentioned we do the inverse of the operation? In this case, 4 is multiplying y. The inverse operation of multiplication is division. So, to get rid of the 4 - we must divide 4y by 4, on both sides.
<em>4y / 4 = 8 / 4
</em>
<em>y = 2
</em>
We now know the variable y is equal to 2.
Hopefully, this helps.
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.
-3x-4= +12
X negative 3 and 4 then add +12 to it.
