I need help with a question regarding Bloom Filters

3. Consider a Bloom Filter scheme to prevent users from choosing passwords from a dictionary. For this problem, assume that your system can hold a Bloom Filter of length 220 (i.e., 2420) while considering storage. For this problem, what is the optimal number of hash functions you need to use? Give an approximate number. Roughly speaking, will these many hash functions assure you that the False Positive Rate of around 5%. 3. Consider a Bloom Filter scheme to prevent users from choosing passwords from a dictionary. For this problem, assume that your system can hold a Bloom Filter of length 220 (i.e., 2420) while considering storage. For this problem, what is the optimal number of hash functions you need to use? Give an approximate number. Roughly speaking, will these many hash functions assure you that the False Positive Rate of around 5%