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There are 5 white socks and 3 black socks in a draw. Steven takes out 2 at random. Work out the probability that Steven takes out 2 socks of the same colour.

P(WW) = 5/8 x 4/7 = 20/56 P(BB) = 3/8 x 2/7 = 6/56 P(same colour) = 20/56 + 6/56 = 26/56 = 13/28 (simplified)
TJ
Answered by Tom J. • Maths tutor
9035 Views

ABC is a right angled triangle. D is the point on AB such that AD = 3DB. AC = 2DB and angle A = 90 degrees. Show that sinC = k/√20 where k is an integer. Find the value of k

AB = 4DB AC = 2DB Find BC using Pythagoras: BC = √(4DB) 2 + (2DB) 2 BC = √20DB 2 = √20 DB sinC = opp/hyp = 4DB/√20DB = 4/√20 so k = 4
TJ
Answered by Tom J. • Maths tutor
16606 Views

Solve 7(k – 3) = 3k – 5

Step 1: 7k-21=3k-5 Step 2: 4k=16 Step 3: k=4
JY
Answered by Jin Yang Q. • Maths tutor
7943 Views

Solve the equation 3x squared + 4x – 12 = 0 Give your solutions correct to 2 decimal places.

3x 2 +4x-12=0 Step 1: formula (-b+/- square root (b 2 -4ac))/2a Step 2: a=3 b=4 c=-12 Step 3: type into your calculator Step 4: answer 1.44, or -2.77
JY
Answered by Jin Yang Q. • Maths tutor
17739 Views

How do you expand brackets?

The easiest method to expand brackets would be to remember FOIL! F - First O - Outside I - Inside L - Last Okay, so lets say you want to expand (3x+1)(2x+3), we'll fist multiply the f irst term of each brack...
CG
Answered by Connor G. • Maths tutor
5973 Views