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3 years ago

14

At how many different times will the digit 7 appear on a digital clock in 24 hours?(show your work and explain your strategy bel

ow)

1 answer:

exis [7]3 years ago

3 0

There are 24 hours in one day. when you count from 1-24, (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24) the number 7 shows up twice

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A quadrilateral has angles that measure 63°, 89° and 121°.

ikadub [295]

The measure of the fourth angel is 87°

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3 years ago

A jeweler wants to make 14 grams of an alloy that is precisely 75% gold.. The jeweler has alloys that are 25% gold, 50% gold, &a

Goryan [66]

Given that the jeweler has alloys that are 25% gold, 50% gold, and 82% gold.

As he wants to make 14 grams of an alloy by adding two different alloys that is precisely 75% gold, so one alloy must have a percentage of gold more than 75%.

One alloy is 82% gold and, the second can be chosen between 25% gold, 50% gold, so there are two cases.

Case 1: 82% gold + 50% gold

Let x grams of 82% gold and y grams of 50% gold added to make x+y=14 grams of 75% gold, so

75% of 14 = 82% of x + 50% of y

$\Rightarrow 75/100 \times 14 = 82/100 \times x + 50/100 \times y \\\\$

$\Rightarrow 75/100 \times 14 = 82/100 \times x + 50/100 \times (14-x)$ [as x+y=14]

$\Rightarrow 75 \times 14 = 82 \times x + 50 \times (14-x) \\\\\Rightarrow 75 \times 14 = 82 \times x + 50 \times14-50\times x \\\\\Rightarrow 75 \times 14 = 32 \times x + 50 \times14 \\\\\Rightarrow 32 \times x =75 \times 14 - 50 \times14 \\\\$

$\Rightarrow x =(25 \times 14)/32=10.9375$ grams

and $y = 14-x= 14-10.9375=3.0625$ grams.

Hence, 10.9375 grams of 82% gold and 3.0625 grams of 50% gold added to make 14 grams of 75% gold.

Case 2: 82% gold + 25% gold

Let x grams of 82% gold and y grams of 25% gold added to make x+y=14 grams of 75% gold, so

75% of 14 = 82% of x + 25% of y

$\Rightarrow 75/100 \times 14 = 82/100 \times x + 25/100 \times y \\\\\Rightarrow 75/100 \times 14 = 82/100 \times x + 25/100 \times (14-x) \\\\ \Rightarrow 75 \times 14 = 82 \times x + 25 \times (14-x) \\\\\Rightarrow 75 \times 14 = 82 \times x + 25 \times14-25\times x \\\\\Rightarrow 75 \times 14 = 57 \times x + 25 \times14 \\\\\Rightarrow 57 \times x =75 \times 14 - 25 \times14 \\\\$

$\Rightarrow x =(50 \times 14)/57=12.28$ grams

and $y = 14-x= 14-12.28=1.72$ grams.

Hence, 12.28 grams of 82% gold and 1.72 grams of 50% gold added to make 14 grams of 75% gold.

3 0

2 years ago

Whats the product of (3-2i) and (7+6i)?

Alona [7]

Answer: the product is = 33+4i

Step-by-step explanation:

21+4i-12i^2

21+4i-12(-1) i^2=-1

21+4i+12

your answer would be 33+4i .

6 0

3 years ago

Area of a rectangle 8cm long and 4cm in height. please tell me how to do this also, I'm so confused.

Tema [17]

The area of a rectangle is easy to compute.
Area = length times height
Area = 8 cm * 4 cm = 32 square centimeters

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3 years ago

An ostrich can run at a rate of 50 miles in 60 minutes.At this rate,how long would it take an ostrich to run 15 miles?

just olya [345]

If an ostrich can run 50 miles in one hour then he can run 12.5 miles in 15 minutes. 15 minutes is 1/4 of an hour. Multiply 50 by 0.25 = 15.

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3 years ago