91Ó°ÊÓ

Find the LCM. \(5,15,18,\) and 20

Multiply or divide the mixed numbers. Write the answer as a mixed number or whole number. $$6 \frac{2}{5} \div(-2)$$

Find the LCM. \(28,10,21,\) and 35

One method for finding prime numbers is the sieve of Eratosthenes. The natural numbers from 2 to 50 are shown in the table. Start at the number 2 (the smallest prime number). Leave the number 2 and cross out every sccond number after the number 2. This will climinate all numbers that are multiples of 2. Then go back to the beginning of the chart and leave the number 3 , but cross out every third number after the number 3 (thus eliminating the multiples of 3 ). Begin at the next open number and continue this process. The numbers that remain are prime numbers. Use this process to find the prime numbers less than 50 . $$\begin{array}{c|c|c|c|c|c|c|c|c|c} & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 \\ \hline 11 & 12 & 13 & 14 & 15 & 16 & 17 & 18 & 19 & 20 \\ \hline 21 & 22 & 23 & 24 & 25 & 26 & 27 & 28 & 29 & 30 \\ \hline 31 & 32 & 33 & 34 & 35 & 36 & 37 & 38 & 39 & 40 \\ \hline 41 & 42 & 43 & 44 & 45 & 46 & 47 & 48 & 49 & 50 \\ \hline \end{array}$$

Add the mixed numbers. $$\begin{array}{r} 2 \frac{1}{11} \\ +5 \frac{3}{11} \\ \hline \end{array}$$

A tile floor is to be made from 10 -in., 12 -in.. and 15 -in. square tiles. A design is made by alternating rows with different-size tiles The first row uses only 10 -in. tiles, the second row uses only 12 -in. tiles, and the third row uses only 15 -in. tiles Neglecting the grout seams, what is the shortest length of floor space that can be covered evenly by each row?

A patient admitted to the hospital was prescribed a pain medication to be given every 4 hr and an antibiotic to be given every 5 hr. Bandages applied to the patient's external injuries needed changing every 12 hr. The nurse changed the bandages and gave the patient both medications at 6: 00 A.M. Monday morning. a. How many hours will pass before the patient is given both medications and has his bandages changed at the same time? b. What day and time will this be?

Add the mixed numbers. $$\begin{array}{r} 5 \frac{2}{7} \\ +4 \frac{3}{7} \\ \hline \end{array}$$

Four satellites revolve around the earth once every \(6,8,10,\) and 15 hr, respectively. If the satellites are initially "lined up," how many hours must pass before they will again be lined up? (IMAGES CANNOT COPY)

Simplify. $$7 \frac{1}{8} \div\left(-1 \frac{1}{3}\right) \div\left(-2 \frac{1}{4}\right)$$