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! = (10Γ9Γ8Γ7Γ6Γ5Γ4Γ3Γ2Γ1)/(6Γ5Γ4Γ3Γ2Γ1Γ4Γ3Γ2Γ1) = 210
Therefore,
= 210 Γ 0.7β΄ Γ 0.3^6
= 0.037