Assume the standard deviation is $410 and that the amounts refunded follow a normal probability distribution. 1. What percent of the refunds are more than $3,100? 2. What percent of the refunds are more than $3,100 but less than $3,500? 3. What percent of the refunds are more than $2,250 but less than $3,500?

Statements reasons 1. ab ? cd; ad ? bc 1. given 2. ac ? ac 2. reflexive property 3. ? adc ? ? cba 3. ? 4. ? dac ? ? bca; ? acd ? ? cab 4. cpctc 5. ? dac and ? bca are alt. int. ? s; ? acd and ? cab are alt. int. ? s 5. definition of alternate interior angles 6. ab ? cd; ad ? bc 6. converse of the alternate interior angles theorem 7. abcd is a parallelogram 7. definition of parallelogram what is the missing reason in step 3?