It is asking you to find the sum of k^2 - 1 from k=1 to k=4. Since that is only 4 numbers, calculating the sum by hand wouldn’t be that bad.
(1^2 - 1) + (2^2 - 1) + (3^2 - 1) + (4^2 - 1) = 26
The easier way to find the sum is to use a few simple formulas.
When we have a term that is just a constant c, the formula is c*n.
When we have a variable k, the formula is k*n*(n+1)/2.
When we have a squared variable, the formula is k*n*(n+1)*(2n+1)/6.
In this case, we have a squared variable k^2 and a constant of -1.
So plug in n=4 to the formulas:
4*5*9/6 - 1*4 = 26
The answer is 26
Answer:

If we compare this value with the 47.3 proposed we have the following error

The computed mean is close to the actual mean because the difference between the means is less than 5%.
Step-by-step explanation:
Assuming the following dataset:
Speed 42-45 46-49 50-53 54-57 58-61
Freq. 21 15 6 4 2
And we are interested in find the mean, since we have grouped data the formula for the mean is given by:

And is useful construct a table like this one:
Speed Freq Midpoint Freq*Midpoint
42-45 21 43.5 913.5
46-49 15 47.5 712.5
50-53 6 51.5 309
54-57 4 55.5 222
58-61 2 59.5 119
Total 48 2276
And the mean is given by:

If we compare this value with the 47.3 proposed we have the following error

The computed mean is close to the actual mean because the difference between the means is less than 5%.
2m-4 = x+nx switch sides
2m-4 = x (1+n) common factor
2m-4/1+4 = x divide both side by 1-x
The answer is A. When 0.7 is put into fraction form it turns into 7/10. Then change the denominator of 3/5 to 10 which makes it 6/10. 7/10 is higher than 6/10 so the answer is A.
Answer:
Step-by-step explanation:
18y