To figure out the cost per cookie, divide $2.49 by 3. The cost per 1 cookie (column 1) would be .83 cents.
To figure out the cost of 20 cookies, multiply 20 x .83 cents. The answer is 20 cookies would cost $16.60
To figure out how many cookies would cost $145,25, divide $145.25 by .83 cents. The answer is 175 cookies would cost $145.25
BE and CD are parallel, so the triangles ABE and ACD are similar. Then the following relation holds:
AE/AD = AB/AC
10/(10 + 8) = x/(x + 6)
Solve for x :
10 (x + 6) = x (10 + 8)
10x + 60 = 18x
8x = 60
x = 60/8 = 7/5
Let the origin of the coordinate system be the position of ship B at noon. Then the distance between the ships as a function of t (in hours) is
.. d = √((30 +23t)² +(17t)²)
.. = √(818t² +1380t +900)
The rate of change of distance with respect to time is
.. d' = (1/2)(2*818*t +1380)/√(818t² +1380t +900)
.. = (818t +690)/√(818t² +1380t +900)
At t=4, this is
.. d' = (818*4 +690)/√(818*16 +1380*4 +900)
.. = 3962/√19508
.. ≈ 28.37 . . . . . knots
The distance between the ships is increasing at about 28.37 knots at 4 pm.
36:96 and 18:48 are both equal to 12:32
Listen in class next time please.