The stem-and-leaf plot shows the number of words in the classified ads in a newspaper one day. How many ads had at least 20, but fewer than 45, words?

1 0 3 3 5 7 9

2 0 0 1 4 5

3 3 8 8

4 7

5 2

key:1|0 = 10

A. 6

B. 3

C. 10

D. 8

Acable company wants to provide cell phone service for residents on an island. the function for the cost of laying the cable from the island to the mainland is c(x)= 6.500 square root x2+4, where x represents the length of the cable in feet. what are the domain and range of the function? a) domain: all real numbers range: all real numbers greater than or equal to 17,000 b) domain: all real numbers greater than or equal to 0 range: all real numbers greater than or equal to 17,000 c) domain: all real numbers greater than or equal to 0 range: all real numbers greater than or equal to 13,000 d) domain: all real numbers greater than or equal to 13,000 range: all real numbers greater than or equal to 0

How to do this , and can some one explain

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document