# Using Operations on Decimals to Solve Problems

Warmup

For each expression below, choose the best estimate of its value.

Activity #1

Estimate Decimals.

• Pull the red slider to locate the decimal on the number line.
• Click . The line will be partitioned to assist you with the right spot.
• Move the green diamond to adjust the location if you didn’t get it the first time. You did well if the revised error is not more than 5%.

Activity #2

Practice Operations on Decimals.

• Solve as many problems as you can to master operations with decimals.

Activity #3

Application of Decimals to Solve Problems.

Below is the diagram of a tennis court. The full tennis court, used for doubles, is a rectangle. All of the angles made by the line segments in the diagram are right angles.

• Study the diagram closely and answer the questions that follow.

(1.) The net partitions the tennis court into two halves. Is each half a square? Explain your reasoning.

(2.) Is the service line halfway between the net and the baseline? Explain your reasoning.

Lines painted on a tennis court are 5 cm wide. A painter made markings to show the length and width of the court, then painted the lines to the outside of the markings

(3.) Did the painter’s mistake increase or decrease the overall size of the tennis court? Explain how you know.

(4.) By how many square meters did the court’s size change? Explain your reasoning.

Challenge #1

The Amazon rainforest covered 6.42 million square kilometers in 1994. In 2014, it covered only as much.

Challenge #2

To get an A in her math class, Jada needs to have at least 90% of the total number of points possible. The table shows Jada’s results before the final test in the class.

(1.) Does Jada have 90% of the total possible points before the final test? Explain how you know.

(2.) Jada thinks that if she gets at least 92 out of 100 on the final test, she will get an A in the class. Do you agree? Explain.

Challenge #2