Astatistician controls by establishing the risk he or she is willing to take in terms of rejecting a true null hypothesis.
a) alpha
b) beta
c) mean
d) standard deviation

a) Alpha

Step-by-step explanation:

The correct option is alpha because alpha known as type I error is the probability of reject the null hypothesis when null  hypothesis is true. If we take alpha 5%, it means that we are taking 5 out of 100 chance of rejecting the null hypothesis when it is true.

So, statistician controls alpha by establishing the risk of rejecting a null hypothesis when its true.

w

step-by-step explanation:

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.