Finding the Fourth Proportional to 138.99, 208.42 and 81.23
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Solution
The fourth proportional to 138.99, 208.42 and 81.23 is: 121.80
Step by Step Solution
- Step 1: Write the proportion equation
138.99 : 208.42 = 81.23 : x - Step 2: Convert to fraction form
138.99/208.42 = 81.23/x - Step 3: Cross multiply
138.99x = 208.42 × 81.23 - Step 4: Simplify right side
138.99x = 16,929.99 - Step 5: Solve for x
x = 16,929.99/138.99 - Step 6: Final answer
x = 121.80
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Why These Related Problems?
These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.