A question such as this one is a little tricky since the people seated are not in a straight line.

For a circular table seating question, (n-1)! formula is used. Without restrictions 5! people can be seated.

You might be wondering why it is not 6!, this is because the first person will the the 6 person so you are accounting for the same person twice.

Hope I helped :)

6 0

3 years ago

A man travels 20 km by car from Town P to Town Q at an average speed of x km/h. He finds that the time of the journey would be s

yuradex [85]

Answer:

x = 20.

Step-by-step explanation:

First, you should remember the relation:

Distance = Speed*Time.

First, we know that a man travels a distance of 20km at a speed of x km/h, in a time T.

We can write this as:

20km = (x km/h)*T

We know that the time is shortened by 12 minutes if the speed is increased by 5km/h

Rewriting these 12 minutes in hours (remember that 60min = 1 hour)

12 min = (12/60) hours = 0.2 hours

Then from this, he can travel the same distance of 20km in a time T minus 0.2 hours if the speed is increased by 5 km/h

We can write this as:

20km = (x + 5 km/h)*(T - 0.2 h)

Then we have a system of two equations, and we want to find the value of x:

20km = (x km/h)*T

20km = (x + 5 km/h)*(T - 0.2 h)

First, we should isolate the variable T in one of the equations, if we isolate it in the first one, we will get:

20km/(x km/h) = T

Replacing that in the other equation we get:

20km = (x + 5 km/h)*(T - 0.2 h)

20km = (x + 5 km/h)*( 20km/(x km/h) - 0.2 h)

Now we can solve this for x.

Removing the units (that we know that are correct) so the math is easier to read, we get:

20 = (x + 5)*(20/x - 0.2)

We only want to solve this for x.

20 = x*20/x - x*0.2 + 5*20/x - 5*0.2

20 = 20 - 0.2*x + 100/x - 1

subtracting 20 in both sides we get:

20 - 20 = 20 - 0.2*x + 100/x - 1 - 20

0 = -0.2*x + 100/x - 1

If we multiply both sides by x we get:

0 = -0.2*x^2 + 100 - x

-0.2*x^2 - x + 100 = 0

This is just a quadratic equation, we can solve it using the Bhaskara's equation, the solutions are:

$x = \frac{-(-1) \pm \sqrt{(-1)^2 - 4*(-0.2)*100} }{2*-0.2} = \frac{1 \pm 9 }{-0.4}$

Then the two solutions are:

x = (1 + 9)/-0.4 = -25

x = (1 - 9)/-0.4 = 20

As x is used to represent a speed, the negative solution does not make sense, so we should use the positive one.

x = 20

then the average speed initially is 20 km/h

3 0

2 years ago

Marina spent $13.50 at the grocery store. She bought pears, kiwis, and pineapples. Pears cost $0.50 each, pineapples cost $1.50

kiruha [24]

Answer:

Number of pineapples = 10

Number of pears = 10 + 9 = 19

Number of kiwis = 10 - 2 = 8

Step-by-step explanation:

Money = $ 13.5

Cost of a pear = $ 0.5

Cost of a pineapple = $ 1.5

Cost of a kiwi = $ 0.3

let the number of pineapple = p

Number of pears = p + 9

Number of kiwis = p - 2

Cost is

0.5 (p + 9) + 0.15 p + 0.3 (p - 2) = 13.5

0.5 p + 4.5 + 0.15 p + 0.3 p - 0.6 = 13.5

0.95 p = 9.6

p = 10

So, number of pineapples = 10

Number of pears = 10 + 9 = 19

Number of kiwis = 10 - 2 = 8

4 0

3 years ago

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