Enter the number of offspring with each combination of traits and the total number of offspring into the calculator to determine the Mendelian ratio.

Mendelian Ratio Formula

The following formula is used to calculate the Mendelian ratio. 

MR = (A / T) : (B / T) : (C / T) : (D / T)

Variables:

  • MR is the Mendelian ratio
  • A is the number of offspring with the first combination of traits
  • B is the number of offspring with the second combination of traits
  • C is the number of offspring with the third combination of traits
  • D is the number of offspring with the fourth combination of traits
  • T is the total number of offspring

To calculate the Mendelian ratio, divide the number of offspring with each combination of traits by the total number of offspring. The resulting ratios represent the statistical probability of offspring inheriting a particular combination of traits from their parents.

What is a Mendelian Ratio?

A Mendelian ratio refers to the predictable patterns of inheritance observed by Gregor Mendel in his genetic experiments with pea plants in the 19th century. These ratios, such as the 3:1 ratio seen in monohybrid crosses or the 9:3:3:1 ratio seen in dihybrid crosses, represent the statistical probability of offspring inheriting a particular combination of traits from their parents. These ratios are foundational principles in the field of genetics.

How to Calculate Mendelian Ratio?

The following steps outline how to calculate the Mendelian Ratio:

  1. First, determine the number of offspring with the first combination of traits (A).
  2. Next, determine the number of offspring with the second combination of traits (B).
  3. Next, determine the number of offspring with the third combination of traits (C).
  4. Next, determine the number of offspring with the fourth combination of traits (D).
  5. Finally, calculate the Mendelian Ratio using the formula: MR = (A / T) : (B / T) : (C / T) : (D / T).
  6. After inserting the values of A, B, C, D, and T into the formula, calculate the result.

Example Problem:

Use the following variables as an example problem to test your knowledge.

A = 25

B = 15

C = 10

D = 20

T = 70