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photoshop1234 [79]
3 years ago
9

A jewelry box with a square base is to be built with silver plated sides, nickel plated bottom and top, and a volume of 30 cm3.

if nickel plating costs $1 per cm2 and silver plating costs $3 per cm2, find the dimensions of the box to minimize the cost of the materials
Mathematics
1 answer:
cupoosta [38]3 years ago
7 0
<span>dimensions of the nickel plated square base: x*x = x^2

height: y

dimensions of the 4 silver plated sides: xy each

dimensions of the nickel plated top: x^2

Volume = 30cm^3 = yx^2 => y = 30 / x^2

Cost of the sides: 4 * xy * $3

Cost ot the top and the bottom: 2 * x^2 * $1

Total cost: 12xy + 2x^2

replace y by 30/x^2

=> cost = 12x * (30/x^2) + 2x^2 = 360 / x + 2x^2

Minimum cost => d [cost] / dx = 0 = - 360/x^2 + 4x =0

=> 90/x^2 - x =0

=> 90 - x^3 = 0

=> x^3 = 90

=> x = ∛(90) = 4.48

=> y = 30 / (4.48)^2 = 1.49

Answer: base: 4.48 cm* 4.48 cm; height: 1.49 cm
</span>
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3 years ago
If n is a positive integer, how many 5-tuples of integers from 1 through n can be formed in which the elements of the 5-tuple ar
sleet_krkn [62]

This question is incomplete, the complete question is;

If n is a positive integer, how many 5-tuples of integers from 1 through n can be formed in which the elements of the 5-tuple are written in increasing order but are not necessarily distinct.

In other words, how many 5-tuples of integers  ( h, i , j , m ), are there with  n ≥ h ≥ i ≥ j ≥ k ≥ m ≥ 1 ?

Answer:

the number of 5-tuples of integers from 1 through n that can be formed is [ n( n+1 ) ( n+2 ) ( n+3 ) ( n+4 ) ] / 120

Step-by-step explanation:

Given the data in the question;

Any quintuple ( h, i , j , m ), with n ≥ h ≥ i ≥ j ≥ k ≥ m ≥ 1

this can be represented as a string of ( n-1 ) vertical bars and 5 crosses.

So the positions of the crosses will indicate which 5 integers from 1 to n are indicated in the n-tuple'

Hence, the number of such quintuple is the same as the number of strings of ( n-1 ) vertical bars and 5 crosses such as;

\left[\begin{array}{ccccc}5&+&n&-&1\\&&5\\\end{array}\right] = \left[\begin{array}{ccc}n&+&4\\&5&\\\end{array}\right]

= [( n + 4 )! ] / [ 5!( n + 4 - 5 )! ]

= [( n + 4 )!] / [ 5!( n-1 )! ]

= [ n( n+1 ) ( n+2 ) ( n+3 ) ( n+4 ) ] / 120

Therefore, the number of 5-tuples of integers from 1 through n that can be formed is [ n( n+1 ) ( n+2 ) ( n+3 ) ( n+4 ) ] / 120

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Mekhanik [1.2K]

The person that completed the 2 miles route first is Lakeisha and he did it in a time of 41.15 minutes

<h3>How to find total time from distance?</h3>

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Thus, the person that will complete the 2 miles route first is the person with the fastest speed which is Lakeisha.

Time he will take to complete the 2 miles route = 2/0.0486 = 41.15 minutes

Read more about time from distance at; brainly.com/question/17146782

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Alina [70]

Answer:

sorry I dont know

Step-by-step explanation: sorry i dont know

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