Answer:
B. 95% confident the average concentration of PCBs in the water supply is between 2.9 ppb and 3.5 ppb
Step-by-step explanation:
You are given the total number of samples, the concentration of lead, and the standard deviation. The standard deviation represents how inaccurate the estimation of the concentration of lead in the drinking water. This means that there can only possibly be a 0.3 ppb error in the estimation. 3.2-0.3=2.9, and 3.2+0.3=3.5
Answer: 42
Step-by-step explanation:
Simply substitute 7 for x.
56 - 2(7)
56 - 14
42
Hope it helps <3
Answer:
2 gallons
Step-by-step explanation:
You have to find the pattern of adding and draining water for 15 days. To get there you need to subtract 2 and add 1 but keep the negative/positives the same i.e. (this is for the 10ths of gallons)
13-2=11
11+1=10
keeping the pattern for 15 days:
+13, 11,+12,-10,+11,-9,+10,-8,+9,-7,+8,-6,+7,-5,+6 = 20 (10ths of gallons)
20/10 = 2