Question

Some time ago , Keith's height and his nephew's height were at a ratio of 15:7. Then, Keiths height increased by 16% and his nephew,s height doubled. Keith is now 34 cm taller than his nephew, what is their total current height

Answer 1

Answer:

The answer is below

Step-by-step explanation:

The ratio of Keith's height and his nephew's height is 15:7. Let keith height be x cm and his nephews height be y cm.

$\frac{x}{y}=\frac{15}{7} \\x=\frac{15}{7}y$

Keiths height increased by 16% , therefore Keith new height is (100% + 16%) × x = 1.16x

The nephew height is doubled, therefore his new height is 2y.

Given that Keith is now 34 cm taller than his nephew

1.16x = 2y + 34

but x = (15/7)y

$1.16(\frac{15}{7} )y=2y+34\\\\\frac{87}{35} y=2y+34\\\\\frac{87}{35} y-2y=34\\\\\frac{17}{35}y=34\\ \\y=\frac{34*35}{17}\\ \\y=70\ cm$

The nephews new height = 2y = 2(70) = 140 cm

Keith new height = 2y + 34 = 140 + 34 = 174 cm

Their total current height = 140 cm + 174 cm = 314 cm