To track the reptile population around a lake, researchers marked 36 turtles. A few weeks later, they counted 400 turtles, of which 20 were marked. To the nearest whole number, what is the best estimate for the turtle population?

720

Step-by-step explanation:

From the question, we are informed that cthe researches counted 400 turtles, of which 20 were marked. This implies that 20/400 = 1/20 were marked.

If the researchers wanted to track the reptile population around a lake, and the researchers marked 36 turtles, the estimate of the total population will then be:

1/20 × x = 36

x/20 = 36

x = 20 × 36

x = 720

The turtle population is 720

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.