1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
adelina 88 [10]
3 years ago
12

A box in a certain supply room contains four 40w, five 60w, and six 75w light-bulbs. suppose that three bulbs are randomly selec

ted.
a.what is the probability that exactly two of the selected bulbs are rated 75w?
b.what is the probability that all three of the selected bulbs have the same rating?
c.what is the probability that one bulb of each type is selected?
d.suppose, now, that bulbs are to be selected one by one until a 75w bulb is found. what is the probability that it is necessary to examine at least six bulbs?
Mathematics
1 answer:
weeeeeb [17]3 years ago
8 0
Situation satisfies the criteria for the use of hypergeometric distribution. Since no replacement is made, binomial distribution is not applicable (probability does not remain constant).

A=number of target wattage bulbs
B=number of non-targeted wattage bulbs
a=number of target wattage bulbs selected
b=number of non-targeted wattage bulbs selected

P(a,b)=C(A,a)*C(B,b)/C(A+B,a+b)
where C(n,x)=combination of x items chosen from n=n!/(x!(n-x)!)

For all following problems, 
A+B=4+5+6=15
a+b=3 (selected)

(a) Target wattage = 75W
A=6, B=9, a=2, b=1
P(a,b,A,B)
=P(2,1,6,9)
=C(6,2)*C(9,1)/C(15,3)
=15*9/455
=27/91

(b) target wattage = each of the three
Probability = sum of probabilities of choosing 3 40,60,75-watt bulbs
P(3x40W)+P(3x60W)+P(3x75W)
Case    (A,B,a,b)
3x40W (4,11,3,0)
3x60W (5,10,3,0)
3x75W(6,9,3,0)

P(3x40W)+P(3x60W)+P(3x75W)
=C(4,3)*C(11,0)/C(15,3)+C(5,3)*C(10,0)/C(15,3)+C(6,3)*C(9,0)/C(15,3)
=4*1/455+10*1/455+20*1/455
=34/455

Can also be solved by elementary counting, for example, for (a),
P(2x75W)
=C(3,2)*6/15*5/14*9/13
=(3)*6/15*5/14*9/13
=27/91 as before
You might be interested in
Julla has 2 identical rooms in her house. If each room measures 8 feet on one side and 12 feet on another, what
Marina CMI [18]

Answer:

The area of a rectangle is one side times the other, and this is the same for two rooms. 2⋅8⋅12=192 square feet.

Step-by-step explanation:

Hoped I helped

8 0
3 years ago
Read 2 more answers
maddy has 5678 memes, she drops 580 of them and gives away 3950 memez. how many memez do i have left ^yes ik the answer i just w
melamori03 [73]

Lol, the answer is 1148

4 0
3 years ago
Read 2 more answers
List the ordered pairs in the equivalence relations produced by these partitions of {a, b, c, d, e, f, g}: a) {a,b},{c,d},{e,f,g
finlep [7]

Answer:

a)  {a,b} , {c,d} , {e,f,g},{a , b } = {(a,a) (b,b) (a,b) (b,a)},{c , d } = {(c,c) (d,d) (c,d) (d , c) } ,{e,f,g} = {(e,e) (e,f)  (f,e) (e,g) (f,f) (f,g) ( g,e) (g,f)(g,g)}  

b) { (a,a)(b,b)(c,c)(c,d)(d,c)(d,d)(e,e)(e,f)(f,e)(f,f)(g,g)

c)  {(a,a)(a,b)(b,b)(b,a)(a,c)(c,a)(b,c)(c,b)(c,c)(d,a)(a,d)(b,d)(d,b)(d,c)(c,d)(d,d)(c,c)(c,f)(f,c)(f,f)(c,g)(g,c)(f,g)(g,f)(g,g)

Step-by-step explanation:

a) {a,b} , {c,d} , {e,f,g}

  {a , b } = {(a,a) (b,b) (a,b) (b,a)}

  {c , d } = {(c,c) (d,d) (c,d) (d , c) }

  {e,f,g} = {(e,e) (e,f)  (f,e)  (e,g) (f,f) (f,g) ( g,e) (g,f) (g,g)}  

b) {a} ,{b},{c,d} ,{e,f},{g}

     { (a,a)(b,b)(c,c)(c,d)(d,c)(d,d)(e,e)(e,f)(f,e)(f,f)(g,g)}

c)  {a,b,c,d},{e,f,g}

   {(a,a)(a,b)(b,b)(b,a)(a,c)(c,a)(b,c)(c,b)(c,c)(d,a)(a,d)(b,d)(d,b)(d,c)(c,d)(d,d)(c,c)(c,f)(f,c)(f,f)(c,g)(g,c)(f,g)(g,f)(g,g)

4 0
3 years ago
Two opposite numbers are 18 units away from each other. What are the numbers?
Oksanka [162]

Answer:

-4 and 4

Step-by-step explanation:

You count between the zeros as when you jump on a number line or just don't count the zero

-4, -3, -2 ,-1, 0, 1, 2 ,3, 4

Hope this helps

5 0
2 years ago
Find the first 3 iterations of the function here: g(n) = 3x if you have<br> an initial value of 2.
Tom [10]
1st it: g(2)=3(2)=6 || 2nd it: g^2(2)=3(6)=18 || 3rd it: g^3(2)=3(18)=54
4 0
3 years ago
Other questions:
  • Two trains leave stations 546 miles apart at the same time and travel toward each other. One train travels at 95 miles per hour
    11·1 answer
  • The table shows the pricing for four different brands of cat food. Brand Cost A $0.88 for 4 oz B $1.05 for 5 oz C $1.60 for 8 oz
    14·1 answer
  • Matrix tossed three coins. What is the probability that all three coins will land on the same side?
    10·1 answer
  • G(n) = 2n + 4<br> f(n) = 2n^2 - 4<br> Find g(n) - f(n)
    10·1 answer
  • Pam is paid $617.83 semimonthly. What is her annual salary?
    6·2 answers
  • What value of x will satisfy the equation:cos( x) = sin( 2x+ 57 )
    13·1 answer
  • Which expression is equivalent to -3 -3x -1 + x
    6·2 answers
  • The function f(x))<br> X. F (x)<br> -6 1<br> -3 2<br> 2. 5<br> 5. 3<br> 8. 0
    9·1 answer
  • Trình bày nội dung của phương pháp bình phương bé nhất. Phân biệt phương pháp
    6·1 answer
  • Find the radius of a circle whose circumference is 9pie
    9·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!