Jim paddles from one shore of a lake 3 miles wide at 4 mph, and john paddles from the opposite shore at 5 mph. how long will they travel before they meet?

a. 3 hours
b. 1 hour, 24 minutes
c. 27 minutes
d. 20 minutes

Option D. 20 minutes.

Step-by-step explanation:

It has been given in the question that distance between the shore of a lake is 3 miles.

Speed of Jim is 4 mph and speed of John is 5 mph.

Let they meet after time t hours.

Therefore distance traveled by Jim in t hours = 4×t miles

and distance traveled by John in t hours = 5×t miles

Total distance they cover = 3 miles.

Now 4t + 5t = 3

9t = 3

t = 3/9 hours.

t = (3×60)/9 minutes.

t = 20 minutes.

Answer is they will meet after 20 minutes.

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.