Answer: 0.038
Step-by-step explanation:
Given: Total games : n= 375
Number of games won by  the team that was winning the game at the end of the third quarter. = 300
The proportion (p) of the team that was winning the game at the end of the third quarter: [tex]p=\dfrac{300}{375}=0.8[/tex]
Critical z-value for 90% confidence: z* = 1.645
Margin of error =[tex]z^*\sqrt{\dfrac{(1-p)p}{n}}[/tex]
The margin of error in a 90% confidence interval estimate of p [tex]=1.645\sqrt{\dfrac{0.2\times0.8}{300}}\\= 1.645\times\sqrt{0.00053333}\\\\=1.645\times0.0231\\\\=0.0379995\approx$0.038[/tex]
Hence, the required margin of error = 0.038