Home / 261-391.68-90

Finding the Fourth Proportional to 261, 391.68 and 90

Calculator

Solution

The fourth proportional to 261, 391.68 and 90 is: 135.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    261 : 391.68 = 90 : x
  2. Step 2: Convert to fraction form
    261/391.68 = 90/x
  3. Step 3: Cross multiply
    261x = 391.68 × 90
  4. Step 4: Simplify right side
    261x = 35,251.20
  5. Step 5: Solve for x
    x = 35,251.20/261
  6. Step 6: Final answer
    x = 135.06

Related Problems

Find fourth proportional to 130.50, 195.84 and 45
Half scale
Find fourth proportional to 522, 783.36 and 180
Double scale
Find fourth proportional to 262, 393.18 and 91
Similar ratio
Find fourth proportional to 391.50, 587.52 and 135
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.