Answer:
Bonds: $42,000
Certificates of deposit: $41,000
Step-by-step explanation:
Total invested = Amount in bonds + Amount in CDs
Amount in bonds = Amount in CDs + 1000
Let the amount in bonds = B and the amount in CDs = C
1. 83,000 = B + C
2. B = C+1000
Since the above expression (#2) defines B, you can substitute it for the B in the first equation (#1).
83,000 = C + 1000 + C
Now, you can solve for C.
83,000 = 2C + 1000
82,000 = 2C
41,000 = C
You know that the amount invested in bonds is $1000 greater than the amount invested in CDs, so add $1000 to C and you find B, $42,000.
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%.
12.74 is the answer to the question
Expanded Notation:
A. 654.362 = (6x100) + (5x10) + (4x1) + (3x0.1) + (6x0.01) + (2x0.001)
B. 125.384 = (1x100) + (2x10) + (5x1) + (3x0.1) + (4x0.01) + (8x0.001)