Final answer:
To calculate the total time for 18 students to each give a 1-minute speech, multiply the number of students by the length of each speech to get 18 minutes. As a mixed number in hours, this is 0 3/10 hours.
Step-by-step explanation:
If each of 18 students gives a 1-minute speech, the total time taken for all the speeches can be calculated by multiplying the number of students by the length of each speech. Therefore, 18 students × 1 minute per student equals 18 minutes in total.
To express 18 minutes as a mixed number in terms of hours, we know that there are 60 minutes in one hour. Thus, 18 minutes is less than an hour. To find the mixed number, we divide 18 by 60, which equals 0.3. Since there are no full hours in 18 minutes, the mixed number is 0 hours and 18/60, which simplifies to 0 hours and 3/10 of an hour. Therefore, it will take 0 hours and 18 minutes for all the speeches to be given, or as a mixed number, 0 3/10 hours.