Probability, ratios and genetic calculations

How do you calculate probability?

Probability = number of favourable outcomes ÷ total number of equally likely outcomes.

How do you convert a probability into a percentage?

Multiply the probability by 100.

How do you convert 1 in 4 into a percentage?

25%.

How do you convert 3 in 4 into a percentage?

75%.

What is the expected dominant-to-recessive phenotype ratio from Aa × Aa?

3:1.

If 100 offspring are produced from Aa × Aa, how many are expected to show the recessive phenotype?

25 on average.

Does a predicted genetic ratio guarantee the exact results?

No. It predicts expected probabilities; actual results may vary, especially with small numbers of offspring.

How do you calculate an arithmetic mean?

Add all the values together and divide by the number of values.

How can a graph help analyse genetic data?

It can show patterns, differences and relationships between variables.

When should estimations be used in genetics calculations?

When an approximate result is sufficient or when checking whether a calculated answer is reasonable.