Home / 616.80-851.40-420

Finding the Fourth Proportional to 616.80, 851.40 and 420

Calculator

Solution

The fourth proportional to 616.80, 851.40 and 420 is: 579.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    616.80 : 851.40 = 420 : x
  2. Step 2: Convert to fraction form
    616.80/851.40 = 420/x
  3. Step 3: Cross multiply
    616.80x = 851.40 × 420
  4. Step 4: Simplify right side
    616.80x = 357,588
  5. Step 5: Solve for x
    x = 357,588/616.80
  6. Step 6: Final answer
    x = 579.75

Related Problems

Find fourth proportional to 308.40, 425.70 and 210
Half scale
Find fourth proportional to 1,233.60, 1,702.80 and 840
Double scale
Find fourth proportional to 617.80, 852.78 and 421
Similar ratio
Find fourth proportional to 925.20, 1,277.10 and 630
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.