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ivann1987 [24]
3 years ago
14

There are 9 boys and 6 girls in a hall, each holding coins in their hand. The mean number of coins for the children is 18 The me

an number of coins for the boys is 14 Work out the mean number of coins for the girls.
Mathematics
1 answer:
Orlov [11]3 years ago
6 0

Answer:

24

Step-by-step explanation:

Average = total number of coins / number of students

If the mean number of coins with boys is 14, the total number of coins held by boys =  14 x 9 = 126

The total number of coins held by the students = total number of children x average number of coins held by the children

15 x 18 = 270

The total number of coins held by girls = 270 - 126 =144

The mean  number of coins for the girls = 144 / 6 = 24

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Anthony decided to buy two DVDs that were not included in the deal. His price after tax was $21.60. What was the cost of the two
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What was the Price before
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3 years ago
Triangle ABC has vertices A(-5, -2), B(7, -5), and C(3, 1). Find the coordinates of the intersection of the three altitudes
Darina [25.2K]

Answer:

Orthocentre (intersection of altitudes) is at (37/10, 19/5)

Step-by-step explanation:

Given three vertices of a triangle

A(-5, -2)

B(7, -5)

C(3, 1)

Solution A by geometry

Slope AB = (yb-ya) / (xb-xa) = (-5-(-2)) / (7-(-5)) = -3/12 = -1/4

Slope of line normal to AB, nab = -1/(-1/4) = 4

Altitude of AB = line through C normal to AB

(y-yc) = nab(x-xc)

y-1 = (4)(x-3)

y = 4x-11           .........................(1)

Slope BC = (yc-yb) / (xc-yb) = (1-(-5) / (3-7)= 6 / (-4) = -3/2

Slope of line normal to BC, nbc = -1 / (-3/2) = 2/3

Altitude of BC

(y-ya) = nbc(x-xa)

y-(-2) = (2/3)(x-(-5)

y = 2x/3 + 10/3 - 2

y = (2/3)(x+2)    ........................(2)

Orthocentre is at the intersection of (1) & (2)

Equate right-hand sides

4x-11 = (2/3)(x+2)

Cross multiply and simplify

12x-33 = 2x+4

10x = 37

x = 37/10  ...................(3)

substitute (3) in (2)

y = (2/3)(37/10+2)

y=(2/3)(57/10)

y = 19/5  ......................(4)

Therefore the orthocentre is at (37/10, 19/5)

Alternative Solution B using vectors

Let the position vectors of the vertices represented by

a = <-5, -2>

b = <7, -5>

c = <3, 1>

and the position vector of the orthocentre, to be found

d = <x,y>

the line perpendicular to BC through A

(a-d).(b-c) = 0                          "." is the dot product

expanding

<-5-x,-2-y>.<4,-6> = 0

simplifying

6y-4x-8 = 0 ...................(5)

Similarly, line perpendicular to CA through B

<b-d>.<c-a> = 0

<7-x,-5-y>.<8,3> = 0

Expand and simplify

-3y-8x+41 = 0 ..............(6)

Solve for x, (5) + 2(6)

-20x + 74 = 0

x = 37/10  .............(7)

Substitute (7) in (6)

-3y - 8(37/10) + 41 =0

3y = 114/10

y = 19/5  .............(8)

So orthocentre is at (37/10, 19/5)  as in part A.

8 0
4 years ago
50pts
lana66690 [7]

Answer:

C is correct.

Step-by-step explanation:

This is true because B and C go up 5 on the y-axis to get to B' and C', but A goes up 6, making it not a translation.

8 0
3 years ago
Read 2 more answers
Explain how u would use the integer tiles to find the quotient of -15 and 3
vova2212 [387]

Answer:

(-15)/3 = -5  

Step-by-step explanation:

(-15)/3

Assume that your positive tiles are yellow, and your negative tiles are red.

The question is asking, "if you take 15 red tiles and split them into three equal groups, how many will you have in each group?"

How can you model the first value of -15?  With 15 red tiles.

Let’s model how to divide the tiles into three equal groups by moving one tile at a time into three separate groups until all 15 tiles have been moved.

Step 1.

Start with 15 red tiles, as in the first picture.

Step 2.

Start by moving tiles one at a time to begin creating three new groups.

The middle picture shows the situation after you have moved the first three tiles.

Step 3.  

Continue moving tiles one at a time from the original group and stacking them evenly in the three new groups until you have no more tiles to move.  

The third picture shows the situation when you have finished.

How many red tiles are in each group?  There are five.

Is the answer positive or negative?  The answer is negative, because there are five red negative tiles in each group.

Conclusion? (-15)/3 = -5

3 0
3 years ago
Read 2 more answers
Which is true about the completely simplified difference of the polynomials 6x6 − x3y4 − 5xy5 and 4x5y + 2x3y4 + 5xy5?
olasank [31]

the difference has 4 terms and a degree of 7

5 0
4 years ago
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