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Finding the Fourth Proportional to 1,258.40, 1,887.90 and 642.20

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Solution

The fourth proportional to 1,258.40, 1,887.90 and 642.20 is: 963.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,258.40 : 1,887.90 = 642.20 : x
  2. Step 2: Convert to fraction form
    1,258.40/1,887.90 = 642.20/x
  3. Step 3: Cross multiply
    1,258.40x = 1,887.90 × 642.20
  4. Step 4: Simplify right side
    1,258.40x = 1,212,409.38
  5. Step 5: Solve for x
    x = 1,212,409.38/1,258.40
  6. Step 6: Final answer
    x = 963.45

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1.5x scale

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.