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Finding the Fourth Proportional to 1,112, 1,668.80 and 428

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Solution

The fourth proportional to 1,112, 1,668.80 and 428 is: 642.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,112 : 1,668.80 = 428 : x
  2. Step 2: Convert to fraction form
    1,112/1,668.80 = 428/x
  3. Step 3: Cross multiply
    1,112x = 1,668.80 × 428
  4. Step 4: Simplify right side
    1,112x = 714,246.40
  5. Step 5: Solve for x
    x = 714,246.40/1,112
  6. Step 6: Final answer
    x = 642.31

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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.