Decimals Round 3 Primary 5

At a science fair, Tasha recorded the weights of three crystals: 1.48g, 2.36g, and 0.97g. She claimed the total weight rounded to the nearest whole number is 5g. Is she correct? Prove your answer with decimal reasoning.

In a relay race, each runner’s time is recorded: Ana ran in 12.48 seconds, Bella in 11.72 seconds, and Carla in 13.35 seconds. The team’s coach says their combined time rounds to 38 seconds. Is he right?

Tyrese claimed that 4.49 rounded to 5. His sister disagreed. Who is correct, and why?

Nina wrote the number 8.72. She says it is composed of 8 ones, 7 tenths, and 2 hundredths. She later tries regrouping it as 7 ones, 17 tenths, and 2 hundredths. Is that valid?

Eli walked three distances during his trip: 3.59 km, 2.48 km, and 1.96 km. He said he walked about 8 km. Is this a reasonable rounding? Show with regrouping.

In a cooking class, a group used 0.4 L of milk, 0.38 L of cream, and 0.17 L of syrup. They think they used about 1 L. Is that true when rounded?

Amaya decomposed 7.86 as 7 + 0.6 + 0.08. Her teacher marked it wrong. Who’s correct? Fix any mistakes.

Jamal has 6.4 meters of wire. He cuts it into two pieces: one measuring 2.75 meters and another measuring 3.56 meters. He thinks he will have some wire left. Is he right? Show your reasoning using decimal regrouping.

At the bakery, Sara bought pastries weighing 1.25 kg, 2.43 kg, and 1.35 kg. She estimated her purchase weighed 5 kg. Use decomposing to check her estimate.

Leo measured the water levels in three aquariums: 4.08 L, 3.7 L, and 2.92 L. He says the total is more than 11 L. Is he right? Compose and regroup the decimals to explain.