Those who use Microsoft Excel only for organizing data into spreadsheets may not be taking advantage of the program's other features, such as the capability to create Venn diagrams and other graphics.

The Venn diagram shows there are \(29 + 22 = 51\) pupils who own exactly one device (this becomes the denominator of the conditional probability). Out of these 51 pupils, 29 own a laptop.

The Venn diagram shows there are \(27 + 41 = 68\) pupils who have a dog (this becomes the denominator of the conditional probability). Out of these 68 pupils, 27 have a cat.