Question 13
(a) Given that Y = and W = , illustrate Y W on the number line.
(b) varies jointly as the square of m and the cube of n. When = 9, m = and n = .
(i) Determine the relationship between x, m and n.
(ii) Calculate, correct to 3 significant figures, the value of:
This question was reported to have been attempted by majority of the candidates and they performed well in it. In part(a), candidates were reported to have obtain Y as which was represented on a number line as { }
1 3 5
In part(b) candidates were expected to show that if x varies jointly as the square of m and the cube of n, then x = km2n3, where x is the constant of proportionality. When = 9, m = and n = , k = = = 9 x = 128. Hence the relationship between x, m and n was x = 128m2n3. When m = , n = , x =128 = or 0.455 correct to 3 significant figures. When x = 5, n = m2 = = = = 20.0. Therefore m = = 4.47 to 3 significant figures.
Question 14 and 15 were not meant for candidates in Nigeria and no response was gotten from the candidates.
and W = 
, illustrate Y 
W on the number line.
varies jointly as the square of m and the cube of n. When 
= 9, m = 
and n = 
.
when m = 
and n = 
; 
when 
= 5 and n = 
. 
In part(a), candidates were reported to have obtain Y
as 
which 
was represented on a number line as { }
= 9, m = 
and n = 
, k = 
= 
= 9 x 
= 128. Hence the relationship between x, m and n was x = 128m2n3. When m = 
, n = 
, x =128
= 
or 0.455 correct to 3 significant figures. When x = 5, n = 
m2 = 
= 
= 
= 20.0. Therefore m = 
= 4.47 to 3 significant figures.