A river flowing southward has a current of 4 miles per hour. A motorboat in still water maintains a speed of 15 miles per hour. The motorboat starts at the west shore on a bearing of N ​40° E. What is the actual speed and direction of the​ boat The actual speed of the boat is approximately
miles per hour

The actual bearing of the boat is north blank degrees east

x > 0, x = 12 miles per hour

Step-by-step explanation:Let x = speed of boat in still water

Speed upstream (against current) = x-4

Speed downstream (with current) = x+4

Distance = (Rate)(Time), so Time = Distance/Rate

Time upstream + Time downstream = 3

16/(x-4) + 16/(x+4) = 3

16(x+4) + 16(x-4) = 3(x+4)(x-4)

                   32x = 3(x2 - 16)

         3x2 - 32x - 48 = 0

        (3x + 4)(x - 12) = 0

          x = -4/3 or x = 12

Since x > 0, x = 12 miles per hour

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.

step-by-step explanation:

a and d