Question

Please help ill give medals & fans.

Dolphins can swim about 20 statute miles per hour. If a dolphin were racing against the yachts in the table, in which place would the dolphin finish? (Hint: Convert the dolphin's average speed from statute miles per hour to knots, to make the comparison.)

A. 3rd place at about 17.4 knots
B. 1st place at about 7.9 knots
C. 2nd place at about 14.7 knots
D. 4th place at about 19.7 knots

*below is the link to the info chart*
http://assets.openstudy.com/updates/attachments/4f90e45de4b000310faef5df-juanito_a-1334895728054-algebra2.png

Answer 1

So you want to convert your statute miles into knots.
Now from the definition... \[ 1 \text{ knot}=\frac{\text{1 nautical mi}}{\text{ 1 h}}\]
We can't use this definition directly just yet because we don't know how many nautical miles are in 1 statute mile. That's why we need the other conversion:
\[ \text{1 nautical mi}=\text{1.15 statute mi}\]

We have 20 statute miles, so:
\[ \text{1 nautical mi}=\text{1.15 statute mi}\\
\text{ ? nautical mi}= 20 \text{ statute mi}\]

You can do a cross-multiplication to find the nautical miles.

Answer 2

so you would get 20=1.15 divide by 20 and get 23 right? @kirbykirby

Answer 3

not quite, more like (20 times 1) divided by 1.15

Answer 4

oh ok and i got 17.4 @kirbykirby

Answer 5

yup :)

Now the next step is to just use the definition of knot, and that's about it

Answer 6

thank you !! do you think you could help me with this one i keep getting 128.6 but it says i am wrong.

Nautical speed was once measured by throwing a rope into the water from the ship. The rope had knots every 47 ft 3 in (47.25 ft), and its wedge-shaped end would "grab" the water. The speed was the number of rope knots that went into the water while a 28-second hourglass ran down. A nautical mile is about 6076 feet. What is the ratio of a nautical mile to the length of the rope between knots?

Answer 7

@kirbykirby