QUESTION #$3.($CHAPTER $2$: UNDERSTANDING MARGINS ACCOUNT WITH EAR$)$

Same information as above question:

Suppose you want to buy $400$ shares of Starbucks $($SBUX$)$ at $$75$ per share. Initial margin requirement is $65\%.$ Call money rate plus the spread is $7\%.$ You supplied cash just to meet the initial margin requirement and invested the rest on margin. Additionally, maintenance margin requirement is $40\%.$

Solve for the following:

$6$ months LATER, suppose the price becomes $$60$ per share. What is your EAR on your margins account? What is the EAR if you had not invested on margin $($i$.$e$.$ using cash account$)?$

$2$ YEARS LATER, suppose the price becomes $$60$ per share. What is your EAR on your margins account? What is the EAR if you had not invested on margin $($i$.$e$.$ using cash account$)?$