For the following set of data, find the number of data within 1 population standard deviation of the mean. Data Frequency 15 1 16 7 17 11 21 13 22 12 25 9 28 6 30 1 i need this quckly please
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1. 2. ∠b and ∠y are right angles. 3.? 4.? which two statements are missing in steps 3 and 4? ∠x ≅ ∠c △abc ~ △zyx by the sas similarity theorem. ∠b ≅ ∠y △abc ~ △zyx by the sas similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem.