How many different trios could be selected from a chorus of 20 singers? 20! c(20, 3) p(20, 3)

C (20, 3) = 1140

Step-by-step explanation:

We are given that there is chorus of 20 singers and we are to find the number of different trios that can be selected from 20 singers.

This is a problem of combinations where the order of trios is not important.

C (20, 3) = 1140

514 m = width of the river to the nearest meter

Step-by-step explanation:

You must memorize the definitions of the trig functions and then these types of problems are easy.

You have a right triangle where the 100 m is the adjacent side to the 79° angle.  You are looking for the side opposite the 79° angle.  So, you need to use the tan function which is defined as opposite side/adjacent side

Let x = the length of the opposite side (width of river)

Tan 79 = x/100

100 tan 79 = x

x = 514 m = width of the river to the nearest meter