3. A magazine collected data on the total cost of the reception at each of a random sample of 80 weddings. The data is grouped and coded using \(y = \frac { C - 3250 } { 250 }\), where \(C\) is the mid-point in pounds of each class, giving \(\sum f y = 37\) and \(\sum f y ^ { 2 } = 2317\).

1. Using these values, calculate estimates of the mean and standard deviation of the cost of the receptions in the sample.
2. Explain why your answers to part (a) are only estimates. The median of the data was \(\pounds 3050\).
3. Comment on the skewness of the data and suggest a reason for it.