If Nora prices each muffin at two dollars, she will sell 1 pack for 2 * 4 = <<1*2*4=8>>8 dollars
Since there are 3 packs to a case, the case will be sold for 3 * 8 = <<3*8=24>>24 dollars
It therefore means that she needs to sell 120/24 = <<120/24=5>>5 cases of muffins.
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