Answer:
20%
Step-by-step explanation:
First month = 4264 phone calls
Second month = 25% more phone calls than the first month
⇒ second month = 4264 × 1.25 = 5330
Third month = 6396 phone calls
[tex]\mathsf{percentage \ change=\dfrac{|final \ value - initial \ value|}{initial \ value}\times 100\%}[/tex]
[tex]\implies \mathsf{percentage \ change=\dfrac{6396 - 5330}{5330}\times 100\%}[/tex]
[tex]\implies \mathsf{percentage \ change=\dfrac{1}{5}\times 100\%}[/tex]
[tex]\implies \mathsf{percentage \ change=20\%}[/tex]