6 (1 point) Researchers at a metals lab are testing a new alloy for use in high end electronics. The alloy is very expensive to make so their budget for testing is limited. The researchers need to estimate the average force required to bend a piece of the alloy to a 90 degree angle. From previous tests, the standard deviation is known to be 20.694 Newtons. In order to estimate the true mean within a margin of error of 7.51 Newtons with 90% confidence, how many samples would need to be tested? 0 1) 20 O 2) We do not have enough information to answer this question since we were not given the sample mean. 0 3) 31 4) 26 5) 21