To solve for sums A, B, and C in the provided problem, we need to add up fractions. However, the exact number of terms in each series is not specified. Still, let's attempt to find the sums based on the visible terms:

### (a) Sum \( A \)

\[ A = \frac{1}{5.6} + \frac{1}{6.7} + \frac{1}{24.25} \]

First, let's convert the fractions to decimal forms and add them up:

\[ \frac{1}{5.6} \approx 0.17857 \]
\[ \frac{1}{6.7} \approx 0.14925 \]
\[ \frac{1}{24.25} \approx 0.04124 \]

Now, adding these values together:

\[ 0.17857 + 0.14925 + 0.04124 \approx 0.36906 \]

Therefore, \( A \approx 0.36906 \).

### (b) Sum \( B \)

\[ B = \frac{4}{11.16} + \frac{4}{16.21} + \frac{4}{21.26} + \frac{4}{61.66} \]

Converting each term to its decimal form:

\[ \frac{4}{11.16} \approx 0.35867 \]
\[ \frac{4}{16.21} \approx 0.24682 \]
\[ \frac{4}{21.26} \approx 0.18809 \]
\[ \frac{4}{61.66} \approx 0.06485 \]

Now, adding these values together:

\[ 0.35867 + 0.24682 + 0.18809 + 0.06485 \approx 0.85843 \]

Therefore, \( B \approx 0.85843 \).

### (c) Sum \( C \)

\[ C = \frac{1}{4} + \frac{1}{28} + \frac{1}{70} + \frac{1}{130} + \frac{1}{208} + \frac{1}{304} + \frac{1}{418} + \frac{1}{550} + \frac{1}{700} + \frac{1}{868} \]

Again, converting each term to its decimal form:

\[ \frac{1}{4} = 0.25 \]
\[ \frac{1}{28} \approx 0.03571 \]
\[ \frac{1}{70} \approx 0.01429 \]
\[ \frac{1}{130} \approx 0.00769 \]
\[ \frac{1}{208} \approx 0.00481 \]
\[ \frac{1}{304} \approx 0.00329 \]
\[ \frac{1}{418} \approx 0.00239 \]
\[ \frac{1}{550} \approx 0.00182 \]
\[ \frac{1}{700} \approx 0.00143 \]
\[ \frac{1}{868} \approx 0.00115 \]

Adding these values together:

\[ 0.25 + 0.03571 + 0.01429 + 0.00769 + 0.00481 + 0.00329 + 0.00239 + 0.00182 + 0.00143 + 0.00115 \approx 0.32258 \]

Therefore, \( C \approx 0.32258 \).

These approximations assume the arithmetic precision is kept simple, and exact values may differ slightly with higher precision calculations.