probability tables: P(|z| < 0.97) = 1- P (|z|>0.97) = 1-2 x P(Z>0.97) = 0.67

[aligator]

Hi

P (|z| < 0.97 ) using probability table (loi normal centrée reduit) the answer is

1- P (|z|>0.97) = 1-2 x P(Z>0.97) = 0.67

At the risk of sounding very stupid how do you get 0.67? 1 tried multiplying 0.97 x2 but not the right answer

Please help. Thanks

 

[Dr.Peterson]

Hi

P (|z| < 0.97 ) using probability table (loi normal centrée reduit) the answer is

1- P (|z|>0.97) = 1-2 x P(Z>0.97) = 0.67

At the risk of sounding very stupid how do you get 0.67? 1 tried multiplying 0.97 x2 but not the right answer

Please help. Thanks

Presumably your table tells you that P(Z>0.97) = 0.1660 (with whatever level of precision it shows). Are you able to find that? Typically, you would look down the left side for "0.9" and read across to the column for "0.07". If you have not learned to read the table, you'll have to show me your table, as they vary.

You seem to have entirely skipped that, and just used 0.97 instead of P(Z>0.97).

Given that result, you just use that number:

1 - 2 * P(Z>0.97) = 1 - 2(0.1660) = 1 - 0.3320 = 0.6680 = 0.67 rounded

 

[aligator]

Presumably your table tells you that P(Z>0.97) = 0.1660 (with whatever level of precision it shows). Are you able to find that? Typically, you would look down the left side for "0.9" and read across to the column for "0.07". If you have not learned to read the table, you'll have to show me your table, as they vary.

You seem to have entirely skipped that, and just used 0.97 instead of P(Z>0.97).

Given that result, you just use that number:

1 - 2 * P(Z>0.97) = 1 - 2(0.1660) = 1 - 0.3320 = 0.6680 = 0.67 rounded

Dear Dr Peterson.

Thanks a million for your rapid reply. It put me on the right track. Indeed I forgot a step. In my table I looked for 0.974 which corresponds to 0.1 in the row and 0.065 in the column (0.165)
1 - (2x 0.165)= 0.67.
Thanks again.