Answer:
21 times 21
Step-by-step explanation:
The spider's movement is an illustration of a parabola.
- The equation of a parabola is:

- The focus of a parabola is: (40,-30)
- The axis of symmetry is:

- The directrix is:

<u>(a) The equation</u>
The spider passes through the origin.
So, we have:

The spider jumps to a maximum height of 10mm, midway 80mm.
So, the vertex is:

The equation of a parabola is:

So, we have:

Subtract 10 from both sides


Solve for a

Substitute
and
in 

<u>(b) The focus, directrix and the axis of symmetry</u>
The focus of a parabola is:

Where:

So, we have:



So, we have:


The axis of symmetry is:

So, we have:

The directrix is:



Read more about parabolas at:
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A Z-score helps us to understand how far is the data from the mean. The number of phones who have battery life in the range of 11.4 to 13 range is 1145.
<h3>What is Z-score?</h3>
A Z-score helps us to understand how far is the data from the mean. It is a measure of how many times the data is above or below the mean. It is given by the formula,

Where Z is the Z-score,
X is the data point,
μ is the mean and σ is the standard variable.
The percentage of phones who have battery life in the range of 11.4 to 13 range is,

= 0.50 - 0.0228
= 0.4772
Now, the number of phones who have battery life in the range of 11.4 to 13 range is,
Number of phones = 0.4772 × 2400 = 1145.28 ≈ 1145
Hence, the number of phones who have battery life in the range of 11.4 to 13 range is 1145.
Learn more about Z-score:
brainly.com/question/13299273
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I think the answer is 126;
Find how long it take to have the same balance
Write the expressions represent the savings of Jen and the savings of Jason
For an instance, w stands for the number of weeks they take to have the same balance.
Jen ⇒ initial $350, additional $25/week, the expression will be
350 + 25w
Jason ⇒ initial $470, additional $15/week, the expression will be
470 + 15w
Then find the value of w using equation Jen's expression and Jason's expression
350 + 25w = 470 + 15w
25w - 15w = 470 - 350
10w = 120
w = 120/10
w = 12
They have the same balance in 12 weeks
Find how much each of them has in 12 weeks
350 + 25w
= 350 + 25(12)
= 350 + 300
= 650
They have each $650 in 12 weeks