Home / 609.40-840.30-388

Finding the Fourth Proportional to 609.40, 840.30 and 388

Calculator

Solution

The fourth proportional to 609.40, 840.30 and 388 is: 535.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    609.40 : 840.30 = 388 : x
  2. Step 2: Convert to fraction form
    609.40/840.30 = 388/x
  3. Step 3: Cross multiply
    609.40x = 840.30 × 388
  4. Step 4: Simplify right side
    609.40x = 326,036.40
  5. Step 5: Solve for x
    x = 326,036.40/609.40
  6. Step 6: Final answer
    x = 535.01

Related Problems

Find fourth proportional to 304.70, 420.15 and 194
Half scale
Find fourth proportional to 1,218.80, 1,680.60 and 776
Double scale
Find fourth proportional to 610.40, 841.68 and 389
Similar ratio
Find fourth proportional to 914.10, 1,260.45 and 582
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.