Answer: 0.037
Step-by-step explanation:
The probability that exactly four of the customers had their problems solved will be 0.037.
Check attachment for further details. Note that 10!/6!4! = (10×9×8×7×6×5×4×3×2×1)/(6×5×4×3×2×1×4×3×2×1) = 210
Therefore,
= 210 × 0.7⁴ × 0.3^6
= 0.037