Suppose the true proportion of Boston residents that are college students is equal to 0.4. If I randomly sample 100 Boston residents, what's the probability that between 35 and 45% are college students

You’re ordering more thread for blue jeans co. you usually purchase from ted’s threads, which sells 12 thread spools for $27. you recently received a notice from wade's wares that says you can buy thread from them for $2.30 each for the first 2 dozen and $2 a spool thereafter. you need to order 5 dozen spools. what percentage can you save by going with wade’s wares?