Answer:
Question 3: 2.7 hours
Question 4: 2.3 hours
Step-by-step explanation:
Question 3:
Time taken by 1st delivery driver = t1 = 6 hours
Time taken by 2nd delivery driver = t2= 5 hours
Time together = T
[tex]{\dfrac{ 1 }{ T } = \dfrac{ 1 }{ t1 } + \dfrac{ 1 }{ t2 }}[/tex]
[tex]{\dfrac{ 1 }{ T } = \dfrac{ 1 }{ 6 } + \dfrac{ 1 }{ 5 }}[/tex]
[tex]{\dfrac{ 1 }{ T } = 0.166+0.2 = 0.366}[/tex]
[tex]{T = \dfrac{ 1 }{ 0.366 } = 2.732}[/tex]
Rounded to the nearest tenth: 2.7 hours
Question 4:
The first valve takes 4 hours to completely drain = t1
[tex]\mathrm{Rate\:for\:first\:valve\:will\:be\:\dfrac{1}{4}\:per\:hour}[/tex]
The second valve taken 5.25 hours to completely drain = t2
[tex]\mathrm{Rate\:for\:second\:valve\:will\:be\:\dfrac{1}{5.25}\:per\:hour}[/tex]
Combined time = T
[tex]{\dfrac{ 1 }{ T } = \dfrac{ 1 }{ t1 } + \dfrac{ 1 }{ t2 }}[/tex]
[tex]{\dfrac{ 1 }{ T } = \dfrac{ 1 }{ 4 } + \dfrac{ 1 }{ 5.25 }}[/tex]
[tex]{\dfrac{ 1 }{ T } = 0.25+0.190 = 0.44}[/tex]
[tex]{T = \dfrac{ 1 }{ 0.44 } = 2.272}[/tex]
Rounded to the nearest tenth: 2.3 hours
