Jack typed 80 words per minute when he enrolled in a typing course. his typing speed increased by 3% two weeks into the course. at the end of the course, jack was able to type his entire 1, 680 word document in 20 minutes. what was the percent of increase in his typing speed from the beginning of the course to the end? a 3% b 4% c 5% d 6% e 7%

The answer is option C : 5%.

Step-by-step explanation:

Jack typed 80 words per minute when he enrolled in a typing course.

His typing speed increased by 3% two weeks into the course.

At the end of the course, Jack was able to type his entire 1, 680 word document In 20 minutes.

Hence, the percent of increase in his typing speed from the beginning of the course to the end is given by:

=5%

Therefore, the answer is option C : 5%.

1/800 is the right answer

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.