Answer:
The student can spend $65 in December.
Step-by-step explanation:
We are given the following in the question:
The spending of 5 months on music must have a mean of $50.
Spending of 4 months:
$40, $25, $55, $90
[tex]Mean = \displaystyle\frac{\text{Sum of all observations}}{\text{Total number of observation}}[/tex]
Let x dollars be the spending of last month. Thus, we can write:
[tex]\Rightarrow \dfrac{40+25+55+90+x}{5} = 55\\\\\Rightarrow 40+25+55+90+x = 275\\\Rightarrow 210 + x = 275\\\Rightarrow x = 65[/tex]
Thus, the student can spend $65 in December.