A 90% confidence interval is found to be (120, 140). What is the margin of
error?

Possible intervals are ( 120 ±12, 140 ±14) , ( 120, 140 ±14)  , ( 120 ±12, 140)

Step-by-step explanation:

Here, we have A 90% confidence interval is found to be (120, 140).

There are various Cases possible as:

Case 1:

There is 10% error in both minimum and extreme values i.e. 120 & 140 ,

Error in 120 is 10% i.e. = 12, Since value can be more or less in error ∴ Error in 120 is ±12.

Similarly, Error in 140 is 10% i.e. = 14, Since value can be more or less in error ∴ Error in 140 is ±14.

Possible intervals are ( 120 ±12, 140 ±14).

Case 2:

There is error in 120 only, ∴ Error in 120 is ±12.

Possible intervals are ( 120 ±12, 140).

Case 3:

There is error in 140 only, ∴ Error in 140 is ±14.

Possible intervals are ( 120, 140 ±14).