Respuesta :
Answer: She have to use her cell phone for 58 minutes in the fourth month.
Step-by-step explanation:
Since we have given that
Number of minutes Grace used her cell phone are as follows :
43 minutes, 62 minutes, 57 minutes, x.
Average = 55 minutes
As we know the formula for "Average":
[tex]Average=\dfrac{43+62+57+x}{4}\\\\55=\dfrac{162+x}{4}\\\\55\times 4=162+x\\\\220-162=x\\\\58=x[/tex]
Hence, She have to use her cell phone for 58 minutes in the fourth month.