Answer:

Step-by-step explanation:
<u><em>the mean in period</em></u> 1 :
(2.3+2.1+2.2+2.2+2.2+2.1+2.4+2.5+2.2+2.0+1.9+1.9+2.1+2.2+2.3)÷15=21.733...
<u><em>the mean in period</em></u> 2 :
(2.3+2.1+3.3+1.5+3.6+1.6+3.0+1.1+4.7+2.1+2.4+1.9+2.8+0.5+2.3)÷15=23.466...
Since 23.466 > 21.733 then “The mean in period 2 is higher than the mean in period 1”.
8-15= -7
x= -7
I think this is correct..
Answer: B and C only
Step-by-step explanation:
The temperature on a cold day starts at 0 degrees Celsius, falls 4 degrees, and rises 4 degrees
Initial temperature = 0
Temperature rise = 4
Fall in temperature = - 4
(Initial temperature + rise in temperature + fall in temperature)
Summing all : (0 + 4 - 4) = 0
carbon atom has 6 negatively charged electrons and 6 positively charged protons.
Net charge of atom :
(number of proton + number of electrons)
( 6 + (-6)) = 0
Pretty sure it's D :)))))