Using the table, give the percentage associated with each unit of standard deviation in the standard normal curve to the
nearest hundredth.
x
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Area, A(x)
0.0793
0.1554
0.2257
0.2881
0.3413
0.3849
0.4192
0.4452
0.4641
0.4772
x
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
Area, A(x)
0.4861
0.4918
0.4953
0.4974
0.4987
0.4993
0.4997
0.4998
0.4999
0.5000
Standard Deviation Percentage Area
-1 to 0
O to +1
O to +2
o to +3
-1 to +2

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places

irst, find the z score of a score of 80. this is given by the formula z = (x-u)/o, where x is the score, u is the mean, and o is the standard deviation. this gives

z = (80-78)/12 = 1/6 = .1667

now, find what percentile a z score of 1/6 correlates to in the normal distribution.

a z score of 1/6 = .1667 is equivalent to the 56.36th percentile of the distribution. so the probability a score is over this is 1-.5636 = .4364

the mean of a sample mean is equal to the original mean. however, the standard deviation of a sample mean is equal to the original standard deviation divided by the square root of n (sample size). so the new standard deviation is 12/sqrt(16) = 3.

the new z score is 80-78/3 = 2/3 = .667. this is equivalent to the 74.86th percentile. so the probability that the mean will be greater than this score is 1-.7486 = .2514.