Is a biased sample valid

How much fence would you need to replace the fence of a 30 foot by 40 foot playground? How much sod would you need to re-sod the lawn?

N/2+5=3 n/2 (as in fractions)

A study attempts to compare two sunscreens. Each of 50 subjects with varying skin complexions will use both sunscreens-Screen A on one side of his or her body and Screen B on the other side.

Photography ahmed needs to take a close-up shot of an prange for his art class. he frames a shot of an orange as shown below, so that the lines of sight form tangents to the orange.

What is the sum of these first 36 terms 1+4+7 + ... + 103+106

Which table represents a linear function that has a slope of 5 and a y-intercept of 20? A 2-column table with 4 rows. Column 1 is labeled x with entries negative 4, 0, 4, 8. Column 2 is labeled y with entries 0, 20, 40, 60.

Scaling up a recipe this recipe makes three dozen cookies. you want to make enough cookies so that 360 people each get two cookies. how will you scale up the recipe? how much of each ingredient will you need?

What i the constant of proportionality in the equation y - 2.5x?

What is the pattern in 1.5,2.75,4

Order the numbers from least to greatest 0.44,4/7,45%