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Finding the Fourth Proportional to 1,113.90, 1,670.39 and 420.19

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Solution

The fourth proportional to 1,113.90, 1,670.39 and 420.19 is: 630.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,113.90 : 1,670.39 = 420.19 : x
  2. Step 2: Convert to fraction form
    1,113.90/1,670.39 = 420.19/x
  3. Step 3: Cross multiply
    1,113.90x = 1,670.39 × 420.19
  4. Step 4: Simplify right side
    1,113.90x = 701,878.05
  5. Step 5: Solve for x
    x = 701,878.05/1,113.90
  6. Step 6: Final answer
    x = 630.11

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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.