Due to which of the following, the irregular variations in a time series are caused:

(A) Floods

(B) Rise in prices before festivals

(C) A fire in a factory

(D) Epidemics

Choose the correct answer from the options given below:

For the values 22, 25, 28, 31, 40, 43, the three yearly moving averages are

The rise in prices of vegetables due to flood is an example of

Which of the following statements are correct?

(A) The method of least squares determines the position of the trend line of the given time series.

(B) The trend line is called the line of best fit.

(C) The line of best fit is a line in which the sum of deviations of the actual values of the variable from their corresponding trend value is always positive.

(D) The normal equations of the trend line $y = a + bx$ are $\sum y = na + b \sum x$ and $\sum xy = a \sum x + b \sum x^2$, where $n$ is the numbers of observations.

Choose the correct answer from the options given below:

For a straight line trend $y_t = a+bx$ for $n$ data by the method of least squares if, $n=8, \sum y=47.8, \sum xy=4.3$ and $\sum x^2=42$, then $y_t$ at $x=-3.5$ is _____.

[where $y_t$ represents trend value of y]

For the given five values 15,24,18,33,42, the three years moving averages are

The number of letters posted in a certain city on each day for a week is given as follows: 40, 55, 28, 25, 31, 52, 43. Which of the following is not an entry in the three-day moving averages?