(a) There are 12 values in the data set which are greater than or equal to 10 and less than or equal to 19.

(b) There are 12 values in the data set which are greater than or equal to 30 and less than or equal to 39.

(c) There are 7 values in the data set which are greater than or equal to 40 and less than or equal to 49.

Step-by-step explanation:

We are given a set of data that is summarized by the stem and leaf plot below;

Steam Leaf

1 0 0 2 4 4 4 7 8 8 8 8 9

2 2 2 5 5 7 8

3 3 4 4 5 5 5 6 6 6 7 9 9

4 3 3 3 5 5 7 9

This shows that the data values are: 10, 10, 12, 14, 14, 14, 17, 18, 18, 18, 18, 19, 22, 22, 25, 25, 27, 28, 33, 34, 34, 35, 35, 35, 36, 36, 36, 37, 39, 39, 43, 43, 43, 45, 45, 47, 49.

(a) From the data above, the number of values in the data set which are greater than or equal to 10 and less than or equal to 19 is 12, i.e; 10, 10, 12, 14, 14, 14, 17, 18, 18, 18, 18, 19.

(b) From the data above, the number of values in the data set which are greater than or equal to 30 and less than or equal to 39 is 12, i.e; 33, 34, 34, 35, 35, 35, 36, 36, 36, 37, 39, 39.

(c) From the data above, the number of values in the data set which are greater than or equal to 40 and less than or equal to 49 is 7, i.e; 43, 43, 43, 45, 45, 47, 49.