HSC Commerce: Marketing and Salesmanship १२ वीं कक्षा - Maharashtra State Board Question Bank Solutions

If x = `y + 1/y`, then `dy/dx` = ____.

Find `"dy"/"dx"` if x = 5t², y = 10t.  

For the following bivariate data obtain the equations of two regression lines:

From the data of 20 pairs of observations on X and Y, following results are obtained.

`barx` = 199, `bary` = 94,

`sum(x_i - barx)^2` = 1200, `sum(y_i - bary)^2` = 300,

`sum(x_i - bar x)(y_i - bar y)` = –250

Find:

1. The line of regression of Y on X.
2. The line of regression of X on Y.
3. Correlation coefficient between X and Y.

Given the following data, obtain a linear regression estimate of X for Y = 10, `bar x = 7.6, bar y = 14.8, sigma_x = 3.2, sigma_y = 16` and r = 0.7

b_YX is ______.

Obtain the trend line for the above data using 5 yearly moving averages.

The data obtained on X, the length of time in weeks that a promotional project has been in progress at a small business, and Y, the percentage increase in weekly sales over the period just prior to the beginning of the campaign.

Find the equation of the regression line to predict the percentage increase in sales if the campaign has been in progress for 1.5 weeks.

If for bivariate data `bar x = 10, bar y = 12,` v(x) = 9, σ_y = 4 and r = 0.6 estimate y, when x = 5.

Fit a trend line to the data in Problem 4 above by the method of least squares. Also, obtain the trend value for the index of industrial production for the year 1987.

The equation of the line of regression of y on x is y = `2/9` x and x on y is x = `"y"/2 + 7/6`.
Find (i) r,  (ii) `sigma_"y"^2 if sigma_"x"^2 = 4`

Identify the regression equations of x on y and y on x from the following equations, 2x + 3y = 6 and 5x + 7y − 12 = 0

Obtain the trend values for the data in using 4-yearly centered moving averages.

If for a bivariate data b_yx = – 1.2 and b_xy = – 0.3 then find r.

From the two regression equations y = 4x – 5 and 3x = 2y + 5, find `bar x and bar y`.

The equations of the two lines of regression are 3x + 2y − 26 = 0 and 6x + y − 31 = 0 Find

1. Means of X and Y
2. Correlation coefficient between X and Y
3. Estimate of Y for X = 2
4. var (X) if var (Y) = 36

Fit a trend line to the data in Problem 7 by the method of least squares. Also, obtain the trend value for the year 1990.

Obtain the trend values for the above data using 3-yearly moving averages.

Find the equation of the line of regression of Y on X for the following data:

n = 8, `sum(x_i - barx).(y_i - bary) = 120, barx = 20, bary = 36, sigma_x = 2, sigma_y = 3`

The following table shows the production of gasoline in U.S.A. for the years 1962 to 1976.

i. Obtain trend values for the above data using 5-yearly moving averages.
ii. Plot the original time series and trend values obtained above on the same graph.