Answer:
Beginning of the month = 3.86 : 1
Feb 3 = 3.86 : 1
Feb 7 = 2.66 : 1
Feb 11= 2.66 : 1
Feb 14 = 3.51 : 1
Feb 18 = 2.82 : 1
Ending of the Month = 2.82 : 1
Explanation:
Effect on current assets and current liabilities for each transaction:
<u>current assets  </u>                                       138,300
collected AR   no effect
 we are chaging one asset (AR) for another (cash)
purchase of long-term asset on cash (43,200)
prepaid insuance for 1 year no effect 
we change one asset (cash) for another(prepaid insurance)
paid account payable                          (12,200)
Ending Current assets                          82,900
<u>current liabilities  </u>              35,800
paid account payable       (12,200)
dividend payable                5,800
Ending current liabilities    29,400
Current ratio:

beginning of the month
138,300 / 35,800 = 3,86
Feb 3 after Ar collected, the ratio is the same as no-change occur
Feb 7 current asset decreased by 43,200
95,100 / 35,800 = 2,66
Feb 11 after the insurance purchase, the ratio is the same as no-change occur
Feb 14 both decrease by 12,200
82,900/23,600 = 3,5127 = 3.51
Feb 18 current liabilities increase by 4,800
82,900 / 29,400 = 2.82