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# A man runs a distance of 9km at a constant speed for the first…

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## A man runs a distance of 9km at a constant speed for the first 4km and then 2km/hr faster for the rest of the distance. The whole run takes him 1 hour. His average speed for the first 4km is

**A.** 6km/hr

**B.** 9km/hr

**C.** 8km/hr

**D.** 11km/hr

**QUICK ANSWER…**

**C**

**DETAILS…**

**Let the average speed for the first 4km be = X**

**Total distance = 9km**

**Speed for the rest of the distance (which is 5km) = X + 2**

**So,**

**But recall that ****distance = speed ****×**** time**

**Total distance = total average speed ****×**** total time**

**Total distance = (X + 1) ****×**** 1 = 9**

**So, X + 1 = 9**

**X = 9 – 1 = 8km/hr**

**Now for the right answer to the above question:**

**Option A is incorrect.****Option B is incorrect.****C is correct.****D is not the correct answer.**

**KEY-POINTS…**

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**/ culled from 2020 JAMB-UTME mathematics past question 01 /**