In acidic medium, KMnO4 accepts 5 e-s , Mn changes its ox. no. from +7 to +2

 KMnO4 + Cu2S = Mn+2 + Cu+2 + SO2

Equivalent of KMnO4 = equivalents of Cu2S

we know, equivalents = n- factors × number of moles

n - factor is defined as change in oxidation number in case of redox reaction .

number of mole of KMnO4 × change in oxidation = number of mole of Cu2S × change in oxidation

number of mole of KMnO4 × (+7 - +2) = number of mole of Cu2S× 2(+2 - +1)

number of mole of KMnO4 × 5 = number of mole of Cu2S ×given, number of mole of Cu2S ( 1.5)

so, number of mole of KMnO4 = 2 × 1.5/5 = 0.6