Emily can ride her scooter 18 miles in 50 minutes. a) i already solved it ; ) b) how long would it take for her to ride 4 miles? c) what is her unit rate in miles per hour?

B) 11.11 (11 rounded); Divide 50 by 18 to get the amount of minutes per mile (2.77) then multiply that by 4 which equals 11.11

C) 21.61 mph (22 rounded) ; There are 10 minutes left until an hour has passed, divide 10 by 2.77 (minutes per mile) to find the distance that would have been traveled (3.61). Finally add the 2 amounts, 18+3.61=21.61

b. astronomers

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.