8th grade math PA PSSA Review 1- no calc

1) Which expression has a value between -4 and -3?

• $1-2\sqrt{10}$

• $4-\sqrt{15}$

• $3\sqrt{5}-7$

• $\sqrt{20}-8$

Solve:  $x^2=144$  

•  $x=12$  

•  $x=\pm12$  

•  $x=72$  

•  $x=\pm72$  

The human body contains about  $2\times10^{12}$   bacteria. The human body contains about  $4\times10^4$  genes. The number of bacteria contained in the human body is how many times as great at the number of genes contained in the human body?

• 500

• 2,000

• 50,000,000

• 200,000,000

The thickness of the skin on the human back is about  $3\times10^{-3}$  meter. The thickness of the skin on the human eyelid is about  $3\times10^{-4}$  meter. How many times as thick is the skin on the human back as on the human eye lid?

• 0.1

• 1

• 10

• 30

A company makes a puzzle that is made of  $5^3$  small plastic cubes. The puzzles are shipped in boxes that each contain  $5^2$  puzzles. The boxes are loaded into truckes that each contain  $5^3$  boxes. What is the total number of small plastic cubes in each truck?

•  $5^8$  

•  $5^{18}$  

•  $125^8$  

•  $125^{18}$  

The volume of Jupiter is approximately $10^{14}$  cubic kilometers. The volume of Earth is approximately  $10^{11}$  cubic kilometers. How many planets the size of Earth does it take to equal the volume of Jupiter?

•  $10^{-3}$  

•  $10^3$  

•  $10^{25}$  

•  $10^{154}$  

Which expression is equivalent to $\left(4^4\right)^2\cdot\left(4^7\right)^{-2}$ ?

•  $\frac{1}{4^6}$  

•  $\frac{1}{4^3}$  

•  $4^{11}$  

•  $4^{30}$  

Which number is the closest approximation of  $\sqrt{39}$ ?

• 6.2

• 6.5

• 7.5

• 7.7

Simplify:  $7^{-8}\times7^{-4}$  

•  $\frac{1}{7^{12}}$  

•  $\frac{1}{7^4}$  

•  $7^{12}$  

•  $7^{32}$