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Finding the Fourth Proportional to 810.40, 1,117.20 and 765.76

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Solution

The fourth proportional to 810.40, 1,117.20 and 765.76 is: 1,055.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.40 : 1,117.20 = 765.76 : x
  2. Step 2: Convert to fraction form
    810.40/1,117.20 = 765.76/x
  3. Step 3: Cross multiply
    810.40x = 1,117.20 × 765.76
  4. Step 4: Simplify right side
    810.40x = 855,507.07
  5. Step 5: Solve for x
    x = 855,507.07/810.40
  6. Step 6: Final answer
    x = 1,055.66

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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.