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Finding the Fourth Proportional to 931.10, 1,280.61 and 781.65

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Solution

The fourth proportional to 931.10, 1,280.61 and 781.65 is: 1,075.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.10 : 1,280.61 = 781.65 : x
  2. Step 2: Convert to fraction form
    931.10/1,280.61 = 781.65/x
  3. Step 3: Cross multiply
    931.10x = 1,280.61 × 781.65
  4. Step 4: Simplify right side
    931.10x = 1,000,988.81
  5. Step 5: Solve for x
    x = 1,000,988.81/931.10
  6. Step 6: Final answer
    x = 1,075.07

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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.