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Finding the Fourth Proportional to 1,080, 1,490.40 and 770.40

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Solution

The fourth proportional to 1,080, 1,490.40 and 770.40 is: 1,063.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,080 : 1,490.40 = 770.40 : x
  2. Step 2: Convert to fraction form
    1,080/1,490.40 = 770.40/x
  3. Step 3: Cross multiply
    1,080x = 1,490.40 × 770.40
  4. Step 4: Simplify right side
    1,080x = 1,148,204.16
  5. Step 5: Solve for x
    x = 1,148,204.16/1,080
  6. Step 6: Final answer
    x = 1,063.15

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.