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Finding the Fourth Proportional to 1,387.99, 1,915.59 and 790.66

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Solution

The fourth proportional to 1,387.99, 1,915.59 and 790.66 is: 1,091.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.99 : 1,915.59 = 790.66 : x
  2. Step 2: Convert to fraction form
    1,387.99/1,915.59 = 790.66/x
  3. Step 3: Cross multiply
    1,387.99x = 1,915.59 × 790.66
  4. Step 4: Simplify right side
    1,387.99x = 1,514,580.39
  5. Step 5: Solve for x
    x = 1,514,580.39/1,387.99
  6. Step 6: Final answer
    x = 1,091.20

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1.5x scale

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.