Hint - Q14

As well as evaluating Z, we also need to find its maximum and minimum possible values.

Since Z = (A - B)/(C - {5 x D}), in order to find Z_max we must make the top of the fraction as large as possible and the bottom of the fraction as small as possible:
        Z_max = (A_max - B_min)/(C_min - {5 x D_max})

Similarly to find Z_min, use Z_min = (A_min - B_max)/(C_max - {5 x D_min})

Having evaluated Z, Z_max and Z_min, the difference between Z and the limiting values is determined, i.e. (Z_max - Z) and (Z - Z_min), and the larger of the two cited as the error.

Question 14

If    Z = (A - B)/(C - 5D)

    and    A = 15.4 ± 0.3,    B = 2.3 ± 0.1,    C = 12.7 ± 0.2,    D = 1.7 ± 0.1

        it can be calculated that    Z = 3.1 ± 0.7

Using worst case scenarios, calculate the value of Z with its associated error. Does your result agree with that stated above?

Yes                No