Home / 386.90-581.70-378.80

Finding the Fourth Proportional to 386.90, 581.70 and 378.80

Calculator

Solution

The fourth proportional to 386.90, 581.70 and 378.80 is: 569.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.90 : 581.70 = 378.80 : x
  2. Step 2: Convert to fraction form
    386.90/581.70 = 378.80/x
  3. Step 3: Cross multiply
    386.90x = 581.70 × 378.80
  4. Step 4: Simplify right side
    386.90x = 220,347.96
  5. Step 5: Solve for x
    x = 220,347.96/386.90
  6. Step 6: Final answer
    x = 569.52

Related Problems

Find fourth proportional to 193.45, 290.85 and 189.40
Half scale
Find fourth proportional to 773.80, 1,163.40 and 757.60
Double scale
Find fourth proportional to 387.90, 583.20 and 379.80
Similar ratio
Find fourth proportional to 580.35, 872.55 and 568.20
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.