Identify missing information

The learner recognizes when a quantitative problem, table, graph, diagram, or verbal description omits a value, unit, condition, or relationship needed to determine an answer, and identifies the missing information by tracing relationships among whole numbers, integers, fractions, decimals, percentages, ratios, and basic geometric measurements. They distinguish information that is uniquely recoverable from information that is insufficient or irrelevant, representing the missing relationship with an equation, proportion, table, or labeled diagram; symbolic parameters, formal systems of equations, and generalized uncertainty are beyond this scope.

Detailed Explanation: Identify missing information

When a problem leaves out a value, first ask:

What value is missing?
What information is needed to find it?
Is there a relationship, rule, or measurement that connects the known and missing values?
Can the missing value be found exactly, or is there not enough information?

Worked example

A rectangular playground has a perimeter of $(46)$ meters. Its length is $(15)$ meters. The diagram does not label the width. What is the width?

Step 1: Identify the missing information

The missing value is the width of the playground.

Step 2: Find the relationship

For a rectangle,

P=2L+2W

where $P$ is perimeter, $L$ is length, and $W$ is width.

Step 3: Substitute the known values

46=2(15)+2W

46=30+2W

Step 4: Solve for the missing value

Subtract $(30)$ from both sides:

16=2W

Divide by $2$ :

W=8

The width is $\boxed{8\text{ meters}}$ .

The perimeter and length were the information needed to recover the missing width. If the problem gave only the length, there would not be enough information to determine the width.

Learn by doing: Identify missing information

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Ratios - Calculate Value from Total Ratio (From Image)

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