Answer:
[tex]C=1.15cents[/tex]
Step-by-step explanation:
Generally the equation for is mathematically given by
Charge Power P=4watts
Rate r=12cents/hour
Time consumed T=24
Generally
Power consumed by smartphone in 24 hours
[tex]P_t=P*T\\\\P_t=24*4[/tex]
[tex]P_t=0.096kwh[/tex]
Therefore the Cost will be
[tex]C=12*0.096kwh[/tex]
[tex]C=1.15cents[/tex]