Answer:
24
Step-by-step explanation:
because i said so
Answer:
-1.2 cm
Step-by-step explanation:
Let's figure out where the ant is after each step.
Step 1
Start at +3.0
Move left <u> - 1.5
</u>
Now at +1.5
Step 2
Start at +1.5
Move right <u> + 4.9
</u>
Now at +6.4
Step 3
Start at +6.4
Move left <u> - 7.6
</u>
Now at -1.2
The ant is now at -1.2 cm.
Well, we could try adding up odd numbers, and look to see when we reach 400. But I'm hoping to find an easier way.
First of all ... I'm not sure this will help, but let's stop and notice it anyway ...
An odd number of odd numbers (like 1, 3, 5) add up to an odd number, but
an even number of odd numbers (like 1,3,5,7) add up to an even number.
So if the sum is going to be exactly 400, then there will have to be an even
number of items in the set.
Now, let's put down an even number of odd numbers to work with,and see
what we can notice about them:
1, 3, 5, 7, 9, 11, 13, 15 .
Number of items in the set . . . 8
Sum of all the items in the set . . . 64
Hmmm. That's interesting. 64 happens to be the square of 8 .
Do you think that might be all there is to it ?
Let's check it out:
Even-numbered lists of odd numbers:
1, 3 Items = 2, Sum = 4
1, 3, 5, 7 Items = 4, Sum = 16
1, 3, 5, 7, 9, 11 Items = 6, Sum = 36
1, 3, 5, 7, 9, 11, 13, 15 . . Items = 8, Sum = 64 .
Amazing ! The sum is always the square of the number of items in the set !
For a sum of 400 ... which just happens to be the square of 20,
we just need the <em><u>first 20 consecutive odd numbers</u></em>.
I slogged through it on my calculator, and it's true.
I never knew this before. It seems to be something valuable
to keep in my tool-box (and cherish always).
Answer: n = 14
Step-by-step explanation: margin of error = critical value × σ/√n
Where σ = population standard deviation = 1
n = sample size = ?
We are to construct a 99% confidence interval, hence the level of significance is 1%.
The critical value for 2 tailed test at 1% level of significance is gotten from a standard normal distribution table which is 2.58
Margin of error = 0.7
0.7 = 2.58×1/√n
0.7 = 2.58/√n
By cross multipying
0.7×√n = 2.58
By squaring both sides
0.7^2 × n = 2.58^2
0.49 × n = 6.6564
n = 6.6564/0.49
n = 14
