Take another look at the sentence:
All of Charlie's hopes sinked when the telephone rang and the beautiful Delores told the eager young man that she didn't have time to study calculus that evening.
The first verb, sinked, is the problem. The sentence requires the simple past. Sank is the correctly spelled form.
|Verb||Simple Present||Simple Past||Past Participle|
Rang, the verb you chose, is perfectly correct. Before you continue, review the rules for irregular verbs.