How to calculate variance from standard deviation.

The two-way table shows the number of people whose hobbies are reading or solving puzzles and who either ride a motorcycle or don’t ride a motorcycle. among people whose hobby is reading, what is the relative frequency of not riding a motorcycle? express your answer as a decimal, and round it to the nearest hundredth if necessary. enter your answer in the box. reading solving puzzles ride a motorcycle 7 3 don't ride a motorcycle 5 9

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

How many grams must be adde to 970g to make 1 and a half kg