Z* for 90% confidence is (hint: use z-table c, or software.) answer to three decimal places x. xxx

We have to find the z critical value at 100% - 90% = 10% level of significance.

Since the normal distribution has two tails, we therefore, need to divide the significance level into two tails with each tail having area of 5%.

Now using the standard normal table, the z critical is:

add an !

step-by-step explanation:

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional