Answer: 2 19/24 hours was spent in practising.
Step-by-step explanation:
During the first hour, they practiced for 5/8 of an hour. During the second hour, they practiced for 2/3 of an hour. This means that the total time for which they practiced in the first 2 hours would be
5/8 + 2/3 = 31/24 hours
During the last two hours, they first practiced for 3/5 of an hour, took a 1/2 hour break and then practiced the rest of the time. This means that the rest of the time for which they practiced is
2 - (3/5 + 1/2) = 2 - 11/10 = 9/10
Therefore, the time they spent practicing in total would be
31/24 + 3/5 + 9/10 = 67/24 =
2 19/24 hours
Answer:
true
Step-by-step explanation:
Answer:

The world population at the beginning of 2019 will be of 7.45 billion people.
Step-by-step explanation:
The world population can be modeled by the following equation.

In which Q(t) is the population in t years after 1980, in billions, Q(0) is the initial population and r is the growth rate.
The world population at the beginning of 1980 was 4.5 billion. Assuming that the population continued to grow at the rate of approximately 1.3%/year.
This means that 
So


What will the world population be at the beginning of 2019 ?
2019 - 1980 = 39. So this is Q(39).


The world population at the beginning of 2019 will be of 7.45 billion people.