Answer:
a) The modal class for this case represent the class with the highest frequency
And for this case would be 
with the highest frequency 8
b) 
Step-by-step explanation:
Part a
The modal class for this case represent the class with the highest frequency
And for this case would be with the highest frequency 8
Part b
For this case we need to find the mid point of each interval:
Interval Midpoint Frequency
18-20 19 3
20-22 21 2
22-24 23 7
24-26 25 8
And we can find the sample mean with this formula:
And replacing we got:
At the beginning, the chances that the teacher will choose a student who has forgotten his lunch are 2/10, or 1/5.
If the teacher now chooses another student from the remaining 9 students, the chances of his choosing a student who has forgotten his lunch are 1/9, since one of the forgetful students has already been removed from the original group of 10 students, and there are only 9 in the group remaining.
The probability that both students forgot lunch is (1/5)(1/9), or 1/45.
Answer:
$3.74 per gallon
Step-by-step explanation:
1. Divide $44.88 by 12
2. The answer will be 3.74
3. Each gallon will cost $3.74
