Yet there is considerable opposition to the use of genetically modified plants for food production and other uses. Genetic engineering offers a time-saving method for producing larger, higher-quality crops with less effort and expense. You are a tomato farmer whose crops are threatened by a persistent species of beetle. 2  Each year, you spend large sums of money for pesticides to protect your crops.
To calculate the variance follow these steps: 1  Work out the Mean (the simple average of the numbers). 2  Then for each number: subtract the Mean and square the result (the squared difference). 3  Then work out the average of those squared differences.
Say we have a bunch of numbers like 9, 2, 5, 4, 12, 7, 8, 11. To calculate the standard deviation of those numbers: 1  1. 2  Work out the Mean (the simple average of the numbers). 3  2. Then for each number: subtract the Mean and square the result. 4  3. Then work out the mean of those squared differences.