Good day! Pls answer what is asked for number 1 and 2. Badly need help. Thank you

Ques:

Due to the pandemic that we are experiencing right now, a researcher (w/ IATF permit) aims to determine the health status of the senior citizens in a certain municipality. The barangays in the municipality have a total population of 11, 926 senior citizens. Determine how many senior citizens will constitute the sample if the margin of error is 1%, 5%, and 10% respectively. Which among these confidence levels is the most reliable and valid to represent the population? And Why?The researcher wants a systematic sampling and the sample size is 98. Determine the following: a. The Sampling interval b. The first two units in the sample if the random start is 2 c. The middlemost unit's in the sample if the random start is 5 d. The last two units in the sample if the random start is 3A population is divided into three strata so that N,= 10, 000 N2= 4,000 and Na= 6,000. Respective standard deviation arc =5, 2=20, 6;= 10. How should a sample size of n = 320 be allocated to the three strata if the researcher wants optimum allocation using disproportionate sampling design