heres what i did on the 2.1.4 practice problem on apex
Step-by-step explanation:
1. Circle the two boats you picked for your trip.
the yacht and the tall ship (aka the pirate ship)
2. Make sense of the problem.
what do you know?
The tall ship makes the trip in 10 hours. The yacht makes the trip in 2.5 hours. The tall ship is 30 knots slower than the yacht.
what do you want to find out?
How fast is each boat traveling in knots (nautical miles per hour)?
what kind of answer do you expect?
probably just some numbers like 10 miles per hour or 40 miles per hour
Writing some expressions
3. Write an expression for the distance going to the island. Let x be the speed of the boat you are taking to the island. Distance is equal to speed times time. (2 points)
the expression would be D = 10(x-30), d is the distance. it could also be simplified to 10x - 300
4. Write an expression for the speed of the boat coming back from the island in terms of the other boat's speed. Let x be the speed of the boat you are taking to the island. (2 points)
so the yacht's speed would be S = x knots, s is for speed.
5. Write an expression for the distance returning from the island. Use the expression for speed you found in question 4. Remember that distance is equal to speed times time. (2 points)
the distance returning from the island would be D = 2.5x.
6. Each ship travels the same distance. Set the distances equal to each other to get the equation for the speed of the ship you are taking to the island. (1 point)
10x - 300 = 2.5x
7. Solve the equation from question 6 for x. What does this tell you? (5 points: 1 point for showing your work, 3 points for solving for x, 1 point for explaining the answer)
10x - 300 = 2.5x
10x - 300 + 300 = 2.5x + 300
10x -2.5x = 300
7.5x = 300
x = 40
x is the speed of the yacht. (40 nautical miles per hour)
8. How fast does the second boat travel? Show your work. (2 points: 1 point for showing your work, 1 point for the answer)
the yacht travels at 40 nautical miles per hour and the tall ship travels at 100 (10x - 300) nautical miles per hour.
9. When you get to the island, you decide to take a kayak tour to a nearby reef. A kayak is a small boat you row with a paddle.
Find the speed for the kayak. Use one of these facts to help.
The steamboat's speed is 4 less than 8 times the speed of the kayak.
The tall ship's speed is 1 more than 3 times the speed of the kayak.
The yacht's speed is 5 less than 15 times the speed of the kayak.
Write and solve an equation for the speed of the kayak. Show your work. (5 points: 2 points for writing a correct equation, 3 points for the solution)
the equation for the speed of the kayak is 40 = 15x - 5, which in this case, x is the speed of the kayak
40 = 15x - 5
40 + 5 = 15x -5 + 5
45 = 15x
x = 3
therefore, the speed of the kayak is 3 nautical miles per hour.
10. The length of your trip to the island is 40 nautical miles less than 20 times the distance to the reef.
It's 2:00 p.m. now, and your boat leaves the island at 7:30 p.m. Will you be able to kayak to the reef and back by then?
If so, how long will you have to spend at the reef?
If not, how late will you be for the return trip?
Explain how you plan to solve this problem. Then solve the problem, showing all work. (5 points: 2 points for the explanation of the plan, 1 point for deciding if you will make it back to the island on time, and 2 points for determining either how long you can spend at the reef or how late you'll be)
the distance to the island is 100 nautical miles, so the expression would be 100 = 20x -40, with x being the distance to the reef.
we can solve for x by doing:
100 = 20x -40
100 + 40 = 20x - 40 + 40
140 = 20x
140 / 20 = x
x = 7
so the distance from my starting point to the reef will be 7 nautical miles, and the distance from the island to the reef would be 93 nautical miles.in that case, I would be like a day and a half late, but if you are trying to say that the ship is waiting for me at the starting point of my "adventure", then I would not be late if I kayak from my starting point to the reef, in fact, I could stay at the reef for like 50 min, because:
7 / 3 = 2 1/3 hours.
2 1/3 x 2 = 4 2/3 hours or 280 min.(to the reef and back)
7:30 p.m. - 2:00 p.m. = 5 1/2 hours or 330 min. (how much time I have till the ship leaves)
330 - 280 = 50 min. (how many min I can spend at the reef)
