Answer:
Step-by-step explanation:
common difference d=3-1=2
first term a=1
an=a+(n-1)d
2n-1=1+(l-1)2
2n-1=1+2l-2
2n-1=2l-1
l=n
(i used l for number of terms)
number of terms=n

So if the ratio is 2:3, then the younger child would represent the 2. so it would be 2:3 is 4:x. Thereby, the answer would be 6, because of proportions. To check, simplify 4:6, and you would get 2:3.
Cos(x) = BC/AB = 10.5/20 = 0.525 ⇒ x = 58.3°
The average speed would be 600 km/hr.
Step-by-step explanation:
Let the original speed be 'x'
Let the decreased speed be 'x-200'
Distance = 600 km
Time increased by 30 minutes
According to question, it becomes,

So, The average speed would be 600 km/hr.
Answer:
Step-by-step explanation:
Given the following scores 3, 7 and 2, we are to find the expression Σ2X-2 and Σ(X-1)²
The value of X's are 3, 7 and 2. Substituting the values we will have;
Σ2X-2 = [2(3)+2(7)+2(2)] - 2
Σ2X-2 = (6+14+4) - 2
Σ2X-2 = 24-2
Σ2X-2 = 22
For Σ(X-1)²
Σ(X-1)² = (3-1)²+ (7-1)² + (2-1)²
Σ(X-1)² = 2²+6²+1²
Σ(X-1)² = 4+ 36+1
Σ(X-1)² = 41