Answer:
9.18%
Step-by-step explanation:
First, find the z-score.
z = (x − μ) / σ
z = (18 − 19.6) / 1.2
z = -1.33
Use a chart or calculator to find the probability:
P(Z < z) = 0.0918
In below formula for arithmetic sequence you can fill in a=7 (start), d=2 (interval) and n=35 (nr terms) and you get
17.5(14 + 34*2) = 1435
Confirmed by a brute-force addition: 7+9+11+13+15+17+19+21+23+25+27+29+31+33+35+37+39+41+43+45+47+49+51+53+55+57+59+61+63+65+67+69+71+73+75=1435
The answer would be (-7x+8), the -1 basically means to switch the symbols
4 x 2 tens = 80, 28 x 14 = 392