This game turns that lookup into a 10-question race: a running score, streak and clock, and the right row and column after every answer, so you get fast and accurate before an exam.
Ten timed lookups. Each one gives a z-score and asks for the area to its left or right. Tap the area you think is right, or type it. The clock starts on question 1. Every answer is a value from the z-table on our homepage.
Positive z-table · Negative z-table · Try it in reverse: Guess the Z
Question: what is the area to the right of z = 2.15?
Step 1. In the positive z-table, go to row 2.1 and column .05: P(Z < 2.15) = 0.98422.
Step 2. The table gives left areas, so subtract from 1: 1 − 0.98422 = 0.01578.
Answer: about 1.6% of the standard normal curve lies to the right of z = 2.15. For a negative z such as −0.84, read the negative z-table directly: row −0.8, column .04 gives 0.20045.
Split z into its first decimal and its second decimal. Go down to the row for the first part (for example 1.3) and across to the column for the second (.07). The cell is the area to the left of z: P(Z < 1.37) = 0.91466.
Look up the left area and subtract it from 1. For z = 2.15 the table gives 0.98422, so the area to the right is 1 − 0.98422 = 0.01578.
Use the negative z-table, or use symmetry: P(Z < −z) = 1 − P(Z < z). For z = −0.84 the negative table gives 0.20045 directly.
You get 10 lookups. Each correct answer adds a point and the clock runs from the first question to the last. Get all 10 right to set a best time, which is saved only in your own browser.
No. Tap one of the four choices, or type the area with 5 decimals (0.91466) or rounded to 4 (0.9147).