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Documenting Problems That Were Difficult To Find The Answer To

Improving Your Success Rate By Re-Taking A Test

I was reading that the pass rate for a particular test was 60%. That doesn’t sound very high – and if I take that exam I have a 40% chance of failing that test.

But what if I retry? Or retry two times? What are my odds of passing in that situation?

Let’s take the example where the average pass rate of an exam is 60%.

Description Math
Let Ppass be the probability of passing Ppass = 0.6
Probability of failing first time is Pfail Pfail = 1 – Ppass = 0.4
Probability of failing two times is Pfail2 Pfail_twice = Pfail * Pfail = 0.4 * 0.4 = 0.16
Probability of not failing two times in a row 1 – Pfail_twice = 1 – 0.16 = 0.84
Probability of not failing is the probability of succeeding 0.84

So if you budgeted to take a test two times, not just once, then the probability you pass the first or second time is a much higher 84%!

You could also calculate what your probability of success is if you took an exam three times!

Here’s a table of exams and what your success rate would be if you undertook exams a different number of times:

Description 10% 20% 30% 40% 50% 60% 70% 80% 90%
one attempt 10% 20% 30% 40% 50% 60% 70% 80% 90%
two attempts 19.0% 36.0% 51.0% 64.0% 75.0% 84.0% 91.0% 96.0% 99.0%
three attempts 27.1% 48.8% 65.7% 78.4% 87.5% 93.6% 97.3% 99.2% 99.9%
four attempts 34.4% 59.0% 76.0% 87.0% 93.8% 97.4% 99.2% 99.8% 100%

The moral of the story is: don’t fear a tough-looking exam with a mere 60% success rate. Know that if you budget the time and expense for taking the test twice you increase your odds of passing to a much higher 84%!

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