Question

Q#29. Visual sequential memory and poor spellers. Holmes, Malone, and Redenbach (2008) found that good readers and good spellers correctly read M = 93.8 (SD = 2.9) words from a spelling list. On the other hand, average readers and poor spellers correctly read M = 84.4 (SD = 3.0) words from the same spelling list. Assuming these data are normally distributed,

(a) What percentage of participants correctly read at least 90 words in the good readers/good spellers group? (use 2 decimal places) HINT: Calculate the z-score first. Then draw and shade the relevant portion of the curve. Finally, look up the proportion in the z table.
%

(b) What percentage of participants correctly read at least 90 words in the average readers/poor spellers group? (use 2 decimal places) HINT: See the hint above. NOTE. Use 84.4 rather than 84.8
%

Answer 1

note : for finding proabability from z score,

1. First look into the z table for row with z score up-to first decimal

2. Look for 2nd decimal value in columns.. If you cannot find it look for the two values between which your value lies. (use interpolation)

3. cross the row and column (found in step 1 & 2) to find your probability value.

This will give proabability for z score below or equal to your calculated value. For P(z> z-score), subtract the former value from 1.