# SBAC Grade 8 Math Practice Test

#### The total length of the world's coastlines is about 315,000 miles. Which answer expresses this in scientific notation?

To write a number in scientific notation, the form is a×〖10〗^n, where 1≤a<10. The decimal need to move 5 spaces to the left so it is immediately to the right of the 3. Because it moved 5 spaces to the left, n=5, so the answer is 3.15×〖10〗^5

#### John’s Gym charges its members according to the equation C=40m where m is the number of months and C represents the total cost to each customer after m months. Ralph’s Recreation Room charges its members according to the equation C=45m. What relationship can be determined about the monthly cost to the members of each company?

In both equations, the coefficient of m is the rate of change. In this problem, the rate of change represents the customer’s monthly cost. Therefore the customers at John’s Gym pay $40 per month, and the customers at Ralph’s Recreation Room pay $45 per month. Thus, John’s monthly membership fee is less than Ralph’s monthly membership fee.

#### Which of the following graphs is not a function?

A function cannot map a single input to more than one output. The vertical line test states that if a vertical line touches a graph in more than one point, then it is not a function. The graph from answer D does not pass the vertical line test so it is not a function.

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