Question

In how many ways can the word "TOPO" be arranged?

a. 12 ways
b. 15 ways
c. 18 ways
d. 21 ways

Answer 1

In how many ways can the word "TOPO" be arranged?

a. 12 ways

b. 15 ways

c. 18 ways

d. 21 ways

Solution

The rule for repeated objects is

$$\frac{n!}{m! \, p! \, \ldots \, q!}$$

where $n$ is number of letters in the word, $m$ – number of repeats of the first letter, ..., $q$ – number of repeats of the last letter.

So we get

$$\frac{4!}{2!} = 12.$$

Answer: a. 12 ways.