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4 years ago

Please someone help me !

Mathematics

1 answer:

brilliants [131]4 years ago

3 0

Step-by-step explanation:

a. If x is the total numbers of students in school, 35%x = 140.

0.35x = 140

x = 140/0.35 = 400

b. Since there are 400 kids in the school, 15% of them take the bus which is 0.15 * 400 = 60 kids.

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3 years ago

Read 2 more answers

David started across a lake 15 miles wide in his fishing boat at 10 miles per hour. He had to row the rest of the way at only 5

schepotkina [342]

Answer:

Total time = 2hrs

Step-by-step explanation:

Firstly, to outline some variables, with which we can construct some equations:

x = the time taken to cross the river at 10mph (in hrs)

y = the time taken to cross the river at 5mph (in hrs)

t = total time taken to cross the river (in hrs)

a = distance travelled at speed 10mph (in miles)

b = distance travelled at speed 5mph (in miles)

Then,

a + b = 15

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y = ¹/₂(t) ∴ t = 2y, so,

x + y = 2y ∴ x = y

Secondly, we know speed = distance/time, so,

10 = a/x ⇒ x = a/10

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So,

a/10 = b/5 ∴ a = 2b

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x = 5/5 = 1,

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t = 2(1) = 2

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