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Finding the Fourth Proportional to 975.12, 1,345.90 and 643.60

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Solution

The fourth proportional to 975.12, 1,345.90 and 643.60 is: 888.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    975.12 : 1,345.90 = 643.60 : x
  2. Step 2: Convert to fraction form
    975.12/1,345.90 = 643.60/x
  3. Step 3: Cross multiply
    975.12x = 1,345.90 × 643.60
  4. Step 4: Simplify right side
    975.12x = 866,221.24
  5. Step 5: Solve for x
    x = 866,221.24/975.12
  6. Step 6: Final answer
    x = 888.32

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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.