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Gekata [30.6K]
3 years ago
13

Write 90% as a decimal and fraction in simplest form

Mathematics
1 answer:
solong [7]3 years ago
5 0
90% as a decimal is .9 and then as a fraction in simplest form is 9/10
Hope it helps
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PRACTISE NOW 11
andriy [413]

Answer:

i. x² + 7x - 16800 = 0 ii. x = 126.16 km/h or -133.16 km/h iii. 5.01 h

Step-by-step explanation:

i. If he drove at an average speed of x km/h on his journey from City P to City Q formulate an equation in x and show that it reduces to x2 + 7x – 16 800 = 0.

For the first journey from City P to City Q, with Mr Lee moving at an average speed of x km/h, he reaches there in time, t and covers the distance, d = 600 km

So, xt = 600 (1)

On his return journey from City Q to CIty P, his average speed increases by 7 km/h, so it is (x + 7)km/h and his time is 15 minutes less than his first journey. 15 min = 15/60 h = 0.25 h, we have that his time for the journey is (t - 0.25) h. Since the distance covered is the same d = 600 km,

We have (x + 7)(t - 0.25) = 600  (2)

Expanding the brackets, we have

xt - 0.25x + 7t - 0.25(7) = 600

xt - 0.25x + 7t - 1.75 = 600

From (1) t = 600/x and xt = 600

Substituting these into the equation, we have

600 - 0.25x + 7(600/x) - 1.75 = 600

simplifying

-0.25x + 4200/x - 1.75 = 600 - 600

-0.25x + 4200/x - 1.75 = 0

multiplying through by x, we have

-0.25x² + 4200 - 1.75x = 0

dividing through by -0.25, we have

-0.25x²/-0.25 + 4200/-0.25 - 1.75x/-0.25 = 0

x² - 16800 + 7x = 0

re-arranging, we have

x² + 7x - 16800 = 0

ii. Solve the equation x² + 7x - 16 800 = 0, giving both your answers correct to  2 decimal places.

Using the quadratic formula, we solve x² + 7x - 16800 = 0 for x

So, x = \frac{-7 +/-\sqrt{7^{2} - 4 X 1 X -16800} }{2 X 1}\\x = \frac{-7 +/-\sqrt{49 + 67200} }{2} \\x = \frac{-7 +/-\sqrt{67249} }{2} \\x = \frac{-7 +/- 259.32}{2} \\x = \frac{-7 + 259.32}{2} or x = \frac{-7 - 259.32}{2} \\x = 252.32/2 or x=  -266.32/2\\x = 126.16 km/hor x = -133.16 km/h

So, x = 126.16 km/h or -133.16 km/h

iii. Find the time taken for the return journey

The time taken for the return journey is t' = t + 0.25. Now. t = 600/x

Since x cannot be negative, we use x = 126.16 km/h.

So, t = 600/x = 600/126.16 = 4.76 h

t' = t + 0.25

t' = 4.76 + 0.25

t' = 5.01 h

3 0
2 years ago
At 3pm corettas shadow is 1.03 meters long. Her height is 1.65 meters at the same time, a trees shadow is 5.57 meters long. How
Komok [63]
3.477 meters long...................
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3 years ago
Help pls due today thanks
Elanso [62]

Answer:

18/3 is 6

-18/3 is -6

-18/(-3) is 6

18/(-3) is -6

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Three electrical appliances each have power ratings of
Natasha_Volkova [10]
30+8/5=31.6 you have to break the whole question down to get the answer.
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Read 2 more answers
List the following fractions from least to greatest. 1/7, 6/7, 4/7, 3/7. Ignore that I chose an answer, I accidentally clicked i
Mumz [18]

Answer:

Step-by-step explanation:

your answer was right XD its 1/7 3/7 4/7 6/7

7 0
3 years ago
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