Home / 517.80-776.70-420.60

Finding the Fourth Proportional to 517.80, 776.70 and 420.60

Calculator

Solution

The fourth proportional to 517.80, 776.70 and 420.60 is: 630.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    517.80 : 776.70 = 420.60 : x
  2. Step 2: Convert to fraction form
    517.80/776.70 = 420.60/x
  3. Step 3: Cross multiply
    517.80x = 776.70 × 420.60
  4. Step 4: Simplify right side
    517.80x = 326,680.02
  5. Step 5: Solve for x
    x = 326,680.02/517.80
  6. Step 6: Final answer
    x = 630.90

Related Problems

Find fourth proportional to 258.90, 388.35 and 210.30
Half scale
Find fourth proportional to 1,035.60, 1,553.40 and 841.20
Double scale
Find fourth proportional to 518.80, 778.20 and 421.60
Similar ratio
Find fourth proportional to 776.70, 1,165.05 and 630.90
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.