A used car dealer wants to know the mean mileage of the cars currently in his lot. Rather than checking all of the cars, he samples 25 cars and finds that the mean mileage of the sample is 12,456.25. Assuming a standard deviation of 225 miles a confidence level of 95%, what is the margin of error for the sample mean? Use z=1.960

answers-
17.64
52.6
88.2
104.67

Given: ab ≅ cd and ad ≅ bc prove: abcd is a parallelogram. 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? triangle angle sum theorem sas congruency theorem sss congruency theorem cpctc