Question

15. During a Grand Prix car race, the tyres on a car are reduced in
mass by 3%. If their mass is 388 kg at the end of the race, what was
their mass at the start?​

Answer 1

AnswEr :

Their mass at the start was 400 kg.

Explanation :

We're given that the tyres on a car during a grand prix race are reduced in mass by 3%. Also, their mass is 388 kg at the end of the race. We've to find the mass at start.

Let's assume that the mass at the start be 'x' .

Now, According to the given conditions,

Tyres on a car during a grand prix race are reduced in mass by 3% and their mass is 388 kg at the end of the race.

Let's form an equation to find the mass at the start.

$: \implies \sf \: \: x - \dfrac{3}{100} \times x = 388 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: {\bf\bigg(x - 3\% \: of \: x \: is \: 388 \bigg)}$

$: \implies \sf \: \: x - 0.03 \times x = 388$

$: \implies \sf \: \: 0.97x= 388$

$: \implies \sf \: \: x= \dfrac{388 }{0.97}$

$: \implies \sf \: \: { \underline{ \boxed{ \bf{ \blue{x= 400 }}}}} \: \bigstar$

Hence, mass at the start was 400 kg.

Answer 2

Solution :-

Let's assume that, the mass at the start be "R".

According to statement,

↪The tyres on a car are reduced in mass by 3%. If their mass is 388 kg at the end of the race.

Mathematically,

$\hookrightarrow \sf R - 3\% \: of \: R \: is\: 388.$

$\hookrightarrow \sf \: R - \frac{3}{100} \times R = 388$

$\hookrightarrow \sf \: R - 0.03 \times R = 388$

$\hookrightarrow \sf \: 0.97R = 388$

$\hookrightarrow \sf \red{R = 400kg}$

Hence,

• The mass at the start was 400kg.