Answer: 13
Althoug each round trip takes 9 minutes and can carry 5 people on the boat, you can not just divide the 20 minutes time by 9 and multiply by 5 to find the number of people that are saved without getting wet.
First trip:
5 people take the boat to the island but only 4 can stay, because one has to return with the boat to the ship to rescue other 4 people.
So, when 9 minutes have passed, 4 people are safe on the island and the boat is again by the ship.
Second trip:
In the second trip, other 4 people are rescued,along with "sailor" who returned in the boat to rescue them.
When it has passed 18 minutes, the boat is next to the ship agin to carry other 4 people before the boat sinks.
This is the last trip before the boat sinks. So, the total number of passengers rescued is 4 + 4 + 5 = 13
Answer:
3/4 or 6/8
Step-by-step explanation:
the thumbtack goes to 12/16 on the ruler which can be simplified to 3/4 or 6/8.
The total R value is computed from the R-values of the components in the stack as ...
(inches of wood)*(R-value of wood) +(inches of fiberglass)*(R-value of fiberglass) +(inches of foam)*(R-value of foam)
= (4 in)(2 /in) +(2 in)(4 /in) +(3 in)(5 /in)
= 8 +8 +15
= 31
The total R-value of the wall is 31.
