21000 = 3400 t + 600 -> 21000 - 600 = 3400 t --> 20400 = 3400 t --> 20400/3400 = t --> t = 6 min
Answer:
1m 54cm
Step-by-step explanation:
10 students at 1m 40cm
15 students at 1m 58cm
13 students at 1m 60cm
Keep in mind that ratio between cm to m is 1cm/0.01m.
So let find the average by converting cm to m first for the 38 students.
10 students: 1m + (40cm)(0.01m/1cm) => 1.4 m
15 students: 1m + 58cm(0.01m/1cm) => 1.58 m
13 students: 1m 60cm(0.01m/1cm) => 1.60 m
so the average is weighted:
(10*1.4 +15*1.58 + 13(1.6))/38
Therefore the average model height is 1.54 m or 1m 54cm
First I will tell you the formula for this, then I will show how we got the formula, then the answer.
Formula -> (x+a)(x-a)=x^2-a^2
We can find this by expanding the 2 ( )
(x+a)(x-a)=x^2+ax-ax-a^2=x^2-a^2
Now we can use this to solve your problem, the 5 is the a in the formula.
(x+5)(x-5)=x^2-5^2=x^2-25. Therefore choosing the 3rd answer choice.
Answer:
I think 3 ............................three
The answer is B. Hope I helped =)