please check my work and answer all questions correctly ?

QUESTION 1 Total varable costs change with changes in volume of activity True O False QUESTION 6 The contribution margin is calculated by taking total sales revenue minus total fixed costs True False QUESTION 7 The contribution martin income statement is used for internal reporting purposes and presents the fixed and variable components of cost information True False QUESTION 10 Hourly wages for assembly workers are a variable cost O True O False QUESTION 13 Contribution margin per unit is calculated by subtracting variable costs per unit and fixed costs per unit from the selling price per unit True False