It looks like you're working on a problem that involves calculating the variance and standard deviation for a set of frequency data related to road service times.

The data in the image you provided is structured as follows:

• Time intervals and their corresponding frequencies are listed, such as:
  • 22-28 minutes with a frequency of 2
  • 29-35 minutes with a frequency of 1
  • 36-42 minutes with a frequency of 2
  • And so on...

It seems your current variance calculation of 43.08 is incorrect, as the correct variance is 50.3, with a standard deviation of 7.1, as given in the solution.

To calculate the variance and standard deviation, we need to follow these steps:

1. Find the midpoint of each time interval (i.e., the average of the upper and lower bounds of each interval).
2. Multiply each midpoint by the corresponding frequency to get the weighted value.
3. Calculate the mean of these weighted values by dividing the total sum by the total frequency.
4. Calculate the variance by taking the squared differences between each midpoint and the mean, multiplying by the corresponding frequency, and dividing by the total frequency.
5. Find the standard deviation by taking the square root of the variance.

If you'd like, I can walk you through the entire calculation process step by step or clarify any specific parts you're unsure about.

Would you like to continue with a detailed solution or just focus on any part of it?