Answer : 0.286
The total number of mice = 21
The number of female mice = 15
Therefore, the number of male mice = 21 - 15
The number of male mice = 6
Number of male mice = 6
The number of female mice = 15
Probability = possible outcomes / total outcomes
Possible outcomes = 6
Total outcomes = 21
Probability = 6/ 21
Probability = 0.286