Answer:
a) Overall average = 76%
b) Average of first and sixth marks = 75%
Step-by-step explanation:
Let's call the marks a, b, c, d, e and f, in this order.
Then, we can write the following equations:
(a+b)/2 = 0.72 -> a + b = 1.44 (eq1)
(b+c)/2 = 0.75 -> b + c = 1.5 (eq2)
(c+d)/2 = 0.77 -> c + d = 1.54 (eq3)
(d+e)/2 = 0.78 -> d + e = 1.56 (eq4)
(e+f)/2 = 0.79 -> e+ f = 1.58 (eq5)
If we sum all equations, we have:
a + 2b + 2c + 2d + 2e = f = 7.62 (eq6)
Then, we make (eq6) - (eq2) - (eq4):
a + b + c + d + e + f = 4.56 (eq7)
a) The find the overall average, we just need to divide (eq7) by 6:
Overall average = (a + b + c + d + e + f)/6 = 0.76 = 76%
b) First we need to make (eq7) - (eq2) - (eq4):
a + f = 1.5
Then, the average is:
Average = (a+f)/2 = 0.75 = 75%
