Probability Distributions - Oxford University Press

Excel solution—Example 5.10
The Excel solution is ill ustrated in Figure 5.13.
➜ Excel Solution
Mean = Cell C5 Value
Standard deviation Cell C6 Value
X = Cell C8 Value
P(X 110) = Cell C12 Formula: =1–C10
From Excel, the NORMDIST() function can be used to calculate P(X ≥ 110) = 0.02275.
❉ Interpretation We observe that the probability that an individual tube length is at
least 110 cms is 0.02275 or 2.3%.
Example 5.11
Figure 5.13
Calculate the probability that X lies between 85 and 105 cms for the problem outlined in
Example 5.10.
In this example we are
required to calculate P(85
≤ X ≤ 105) which represents
the area shaded in
Figure 5.14.
The value of P(85 ≤ X
≤ 105) can be calculated
using Excel’s NORMDIST()
function.
Figure 5.14
P(85