Question

A body travels a distance of 20m in the 7th second and 24m in the 9th second. How much distance shall it travel in the 15th second?

Answer 1

36 m

Step-by-step explanation:

We can consider this to be an AP.

Then,

• a₇ = 20
• a₉ = 24

Subtract a₇ from a₉.

• a + 8d - a + 6d = 24 - 20
• 2d = 4
• d = 2

• a + 6(2) = 20
• a = 8

Finding a₁₅

• a₁₅ = a + 14d
• a₁₅ = 8 + 14(2)
• a₁₅ = 8 + 28
• a₁₅ = 36 m

Answer 2

• f(7)=20
• f(9)=24

Find rate of change

• f(9)-f(7)/9-7
• 24-20/9-7
• 4/2
• 2m/s

So

Distance travel in 6 s

• Speed×Time
• 6(2)
• 12m

Distance in 15s:-

• 12+24
• 36m