6.6.4 SPM practice 3 (Linear Law) – Question 4

Question 4
The table below shows the corresponding values of two variables, x and y, that are related by the equation y = q x + p q x , where p and q are constants.


One of the values of y is incorrectly recorded.
(a) Using scale of 2 cm to 5 units on the both axis, plot the graph of xy against x 2  .  Hence, draw the line of best fit

(b) Use your graph in (a) to answer the following questions:
(i) State the values of y which is incorrectly recorded and determine its actual value.
(ii) Find the value of p and of q.

Solution
Step 1 : Construct a table consisting X and Y.


Step 2 : Plot a graph of Y against X, using the scale given and draw a line of best fit


Steps to draw line of best fit – Click here

(b) (i) State the values of y which is incorrectly recorded and determine its actual value.


Step 3 : Calculate the gradient, m, and the Y-intercept, c, from the graph

Step 4 : Rewrite the original equation given and reduce it to linear form

Step 5 : Compare with the values of m and c obtained, find the values of the unknown required

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