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Finding the Fourth Proportional to 1,421.09, 2,128.53 and 689.13

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Solution

The fourth proportional to 1,421.09, 2,128.53 and 689.13 is: 1,032.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,421.09 : 2,128.53 = 689.13 : x
  2. Step 2: Convert to fraction form
    1,421.09/2,128.53 = 689.13/x
  3. Step 3: Cross multiply
    1,421.09x = 2,128.53 × 689.13
  4. Step 4: Simplify right side
    1,421.09x = 1,466,838.57
  5. Step 5: Solve for x
    x = 1,466,838.57/1,421.09
  6. Step 6: Final answer
    x = 1,032.19

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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.