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In a class of 30, the ratio of boys to girls is 2 : 3 , how many girls are there?

If the ratio is 2 : 3 then in a class of 5 there would be 2 boys and 3 girls. So we can say that 2/5 of the class are boys and 3/5 of the class are girls. And we know that to calculate 3/5 of 30 we must firs...
RE
Answered by Rebecca E. • Maths tutor
49549 Views

y = 2x + 5, Calculate x when y = 4

y = 2x + 5 y = 4, therefore 2x + 5 = 4 2x = 1 x = 1/2
JT
Answered by Jacob T. • Maths tutor
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A man stands 9 metres from the base of a tree. He knows the distance from where he is standing and the top of the tree is 15 metres. How tall is the tree?

a 2 + b 2 = c 2 a : 9 b : unknown c: 15 b 2 =c 2 - a 2 so b 2 = 225 - 81 =144 so b=12
JM
Answered by Jack M. • Maths tutor
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The mean of 5 numbers is 42. The 5 numbers are 45,29,63,42 and X. Find the value of X.

42 x 5 = 210. 45+29+63+42 = 179. 210 - 179 = 31 X = 31
JF
Answered by Joseph F. • Maths tutor
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Express 3x^2+18x-1 in the form a(x+b)^2 +c

3x^2+18x-1 Bracket out 3x^2+18x Factorise by bringing out the common factor of 3 = 3(x^2+6x) Divide the x coefficient by 2 = 3(x^2+3x) And then remove the square on the x^2 variable and add a square to the o...
CO
Answered by Chukwudi O. • Maths tutor
14551 Views