**Calculating Coefficient of Concurrent Deviation**

To calculate the coefficient of concurrent deviation, we need to follow certain steps. Let us discuss them one by one.

**Step 1: Write Down the Observations**

The first step is to write down the observations. In this case, we have 10 pairs of observations.

**Step 2: Calculate the Mean of Each Pair**

The next step is to calculate the mean of each pair. To do this, we add the two observations in each pair and divide the sum by 2.

**Step 3: Calculate the Deviation of Each Observation from its Respective Mean**

The third step is to calculate the deviation of each observation from its respective mean. To do this, we subtract the mean of each pair from its respective observation.

**Step 4: Calculate the Sum of the Products of Deviations**

The fourth step is to calculate the sum of the products of deviations. To do this, we multiply the deviation of the first observation in each pair with the deviation of the second observation in the same pair. We then add up all the products.

**Step 5: Calculate the Coefficient of Concurrent Deviation**

The final step is to calculate the coefficient of concurrent deviation. To do this, we divide the sum of the products of deviations by the product of the standard deviations of the two sets of observations.

In this case, we are given that the number of concurrent deviations is 4. However, we do not have the actual observations or their standard deviations. Therefore, we cannot calculate the coefficient of concurrent deviation.

**Conclusion**

To calculate the coefficient of concurrent deviation, we need to have the actual observations and their standard deviations. Without this information, we cannot calculate the coefficient of concurrent deviation.

-1/3