Answer: 
Step-by-step explanation:
The pool of rats from which the researcher is drawing participants is composed of the following:
23 male albino rats
21 male spotted rats
35 female albino rats
11 female spotted rats
Total rats = 23+21+35+11 =90
After drawing first rat , total rats remained = 89

The probability of choosing a male albino rat and then either a female albino rat or a male spotted rat = 
Answer:
5(2a -5 + b)
Step-by-step explanation:
(10a - 25 + 5b) = 5( 2a - 5 + b)
5(b + 2a - 5) = 5(2a - 5 + b)
Answer:
1/2^4
Step-by-step explanation: