20% of the student body of Tyson Middle School is in the band. If the student population of Tyson Middle School is 680. how many students are in the band? A. 68
B. 136
C. 78
D. 120 ​

Nine more than four times a number is the same as one less than twice the number. find the number?

Atype of plant is introduced into an ecosystem and quickly begins to take over. a scientist counts the number of plants after mmonths and develops the equation p(m)= 19.3(1.089)^m to model the situation. most recently, the scientist counted 138 plants.assuming there are no limiting factors to the growth of the plants, about how many months have passed since the plants werefirst introduced? a)o 6.1b)0.6.6c)10 72d)o 23.1

Events a and b are independent. the probability of a occurring is 2/5. the probability of b occurring is 1/4. what is p(a and b)?