F(13) means x equals 13.
Replace x in the equation with 13 and solve:
-13 + 3 = -10
F(13) = -10
13, because 78 postcards divided by 6 cards per board = 13 poster boards
Answer:
Sabemos que:

y tenemos que:

Con esto podemos encontrar el valor de a:
8*a/(a+ 4) = 6
8*a = 6*(a + 4) = 6*a + 24
8a - 6a = 24
2a = 24
a = 24/2 = 12.
Tambien sabemos que:

Y de ahí podemos despejar b:
(16*b)/(b + 8) = 12
16*b = 12*(b + 8) = 12b + 96
16b - 12b = 96
4b = 96
b = 96/4 = 24
Entonces tenemos a = 12 y b = 24, y el MH de a y b es:
MH(12,24) = 2*12*24/(12 + 24) = 24*24/36 = 16
Answer:
Mean age: 48
Standard deviation: 4
Step-by-step explanation:
a) Mean
The formula for Mean = Sum of terms/ Number of terms
Number of terms
= 42 + 54 + 50 + 54 + 50 + 42 + 46 + 46 + 48+ 48/ 10
= 480/10
= 48
The mean age is 48
b) Standard deviation
The formula for Standard deviation =
√(x - Mean)²/n
Where n = number of terms
Standard deviation =
√[(42 - 48)² + (54 - 48)² + (50 - 48)² +(54 - 48)² + (50 - 48)² +(42 - 48)² + (46 - 48)² + (46 - 48)² + (48 - 48)² + (48 - 48)² / 10]
= √-6² + 6² + 2² + 6² + 2² + -6² + -2² + -2² + 0² + 0²/10
=√36 + 36 + 4 + 36 + 4 + 36 + 4 + 4 + 0 + 0/ 10
=√160/10
= √16
= 4
The standard deviation of the ages is 4