Let 
be the 20 marks of the boys, and 
be the 10 marks of the girls.
We know that the global mean was 70, meaning that
Multiplying both sides by 30 we deduce that the sum of the scores of the whole classroom is
By the same logic, we work with the marks of the boys alone: we know the average:
And we deduce the sum of the marks for the boys:
Which implies that the sum of the marks of the girls is 
And finally, the mean for the girls alone is
Given:
side lengths of right triangles = 12 cm ; 16 cm ; 20 cm
lateral area = 192 cm²
lateral area of a triangular prism = perimeter * height
192 cm² = (12 cm + 16 cm + 20 cm) * height
192 cm² = 48 cm * height
192 cm² / 48 cm = height
4 cm = height
The height of the pedestal in the shape of a triangular prism is 4 cm.
This load will weigh
1.5 TONS ALTOGETHER.
So, the truck is delivering a
ton of cement blocks, and a
of bricks. To find how much this load weighs, we'd have to add the two fractions together, which proves to be quite easy, because the denominators are already the same, so we wouldn't have to change anything.
+
=
And now, we would want to convert that fraction into a whole number, or at least a decimal, to find how many tons the truck is carrying. So we would divide. Once the work is done, here is what would happen:
12 ÷ 8 = 1.5
And there's your answer. The truck is carrying
1.5 TONS.
Answer:
0.033547 I think
Step-by-step explanation:
This is exponential decay which can be expressed as:
y=ab^t, y=final value, a=initial value, b=rate, t=time
In this case a=25000, r=(100-20)/100=0.8 so
y=25000(0.8^t), so in 4.5 years...
y=25000(0.8^4.5)
y≈$9158.93 (to nearest cent)
